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Latest news

on explosion protection

Electrical equipment for the low voltage area,

legal principles, ATEX guidelines and

types of ignition protection, modular design

structure, VEM product range, repair,

maintenance and conversion

Manual 2013



Authors:

Dr.-Ing. Christian Lehrmann,

Physikalisch-Technische Bundesanstalt Braunschweig

Dipl.-Phys. Dirk Seehase, Dipl.-Ing. Manfred Sattler,

VEM motors GmbH, Wernigerode

Dipl.-Ing. Michael Gruner, VEM motors Thurm GmbH, Zwickau



Latest news

on explosion protection

Electrical equipment for the low voltage area,

legal principles, ATEX guidelines and

types of ignition protection, modular design

structure, VEM product range, repair,

maintenance and conversion

Manual 2013



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Contents Seite

0. Preface 31 The explosion-protected drive – Introduction 61.1 Summary of the legal principles for explosion protection 81.2 Summary of types of ignition protection for gas explosion protection 91.3 Explanation of the general requirements, the types of ignition protection and areas of application 101.3.1 General requirements (gas and dust) 101.3.2 Types of ignition protection 111.3.2.1 Type of ignition protection – Flameproof enclosure “d” 111.3.2.2 Type of ignition protection – Increased safety “e” 111.3.2.3 Type of ignition protection – “n” (non sparking) 121.3.2.4 Type of ignition protection – Pressurized enclosure “p” 121.3.2.5 Type of ignition protection – Powder filling “q” 121.3.2.6 Type of ignition protection – Oil immersion “o” 121.3.2.7 Type of ignition protection – Intrinsic safety “ia/ib” 131.3.2.8 Type of ignition protection – Encapsulation “m” 131.4 Summary of types of ignition protection for dust explosion protection 13

1.4.1 Type of ignition protection – Protection by “tD” housing 141.4.2 Type of ignition protection – Protection by “tx IIIY Dx” housing 141.4.3 Type of ignition protection – Pressurized enclosure “pD” 151.4.4 Type of ignition protection – Intrinsic safety “iD” 151.4.5 Type of ignition protection – Encapsulation “mD” 151.5 Markings complying with different editions of the standard 161.6 Electric motors – Mechanical structure and main focuses of design for conformity with explosion protection 181.7 High-voltage tests on windings under gas 221.8 Setting up and electrical connection 22

2 Technologies for protecting induction machines from prohibited temperature risesas a result of overload – Summary complying with explosion protection 25

2.1 What legal/normative specifications exist regarding protection of electrical machines in explosion-hazard areas? 252.2 Causes of prohibited high temperatures in an electrical machine 262.3 Protection principles for mains-operated machines and

requirements of protection with explosion-protected drives 272.3.1 Type of ignition protection – Flameproof enclosure “d” 272.3.2 Type of ignition protection – Pressurized enclosure “p” 282.3.3 Type of ignition protection – Increased safety “e” 282.3.4 Type of ignition protection – “n” 282.3.5 Type of ignition protection – “t”, dust explosion protection 282.3.6 Direct temperature monitoring 282.3.7 Current-dependent, time-delayed safety equipment 282.3.8 Protection selection and parameterisation with type of ignition protection Increased safety “e” 29

2.3.9 Current and temperature monitoring 302.4 The motor in combination with other equipment 302.4.1 Recommended maximum interface temperatures for flange motors 312.4.1.1 Machines of type of ignition protection Flameproof enclosure “d” in mains operation 312.4.1.2 Machines of type of ignition protection Flameproof enclosure “d” in converter mode 312.4.1.3 Machines of type of ignition protection Increased safety “e”, temperature category T3 32

3 Frequency-converter operated explosion-protected drives and safety measures 323.1 Electrical discharges 323.2 Hot surfaces 333.3 Harmonic losses 353.4 Increase in energy efficiency 35

3.5 Summary and outlook 363.6 Operation on frequency converter with use in Zone 2 (Ex II 3G) or Zone 22 (Ex II 3D) 373.7 Operation on frequency converter with use in Zone 21 (Ex II 2D) 383.8 Operation on frequency converter with use in Zone 1 (Ex II 2G) 383.9 Permanent-magnet synchronous machines 39

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4 The VEM product range of explosion-protected equipment 404.1 Overview 404.2 Energy efficiency and explosion protection 404.3 Gas-explosion protected motors 414.3.1 Motors with squirrel-cage rotor, type of ignition protection Flameproof enclosure “d/de” 414.3.2 Motors with squirrel-cage rotor, type of ignition protection – Increased safety “e” 424.3.3 Motors with squirrel-cage rotor, type of ignition protection – “n” 434.4 Dust-explosion protected motors 434.4.1 Motors with squirrel-cage rotor for use in the presence of combustible dusts, Zone 21 434.4.2 Motors with squirrel-cage rotor for use in the presence of combustible dusts, Zone 22 444.5 Combinations of gas-explosion protection or dust-explosion protection 44

5 Maintenance and repair 45

6 Repair and modification of electrical equipment 46

6.1 General 466.2 Repair tasks not affecting the explosion protection 466.3 Repair tasks requiring inspection by an officially-recognized, qualified person 476.4 Repair tasks on Ex e motors (modifications), which require a new type approval (e. g. by a notified body complying with RL 94/9/EC) 476.5 Repair tasks on Ex d motors (modifications) which require a new type approval (e. g. by a notified body complying with RL 94/9/EC) 486.6 Summary 48

7 Testing the motors after repairs or modifications 487.1 Visual check 497.1.1 Visual check of winding – main points 49

7.1.2 Visual check of complete motor – main points 497.2 Winding test 497.2.1 Winding resistance 497.2.2 High-voltage test 497.2.3 Insulation value (insulation resistance) 497.3 Test run 507.3.1 Rotating field (direction of rotation check) 507.3.2 No-load test, detection of no-load current I

0 50

7.3.3 Evidence of phase symmetry 507.3.3.1 Short-circuit tests with I

B 50

7.3.3.2 Short-circuit test complying with EN 60034-1 507.3.4 Vibration test 517.4 Painting and impregnation after repair work 51

7.5 Documentation of testing 52

8 Summary of standards and regulations 538.1 General standards 538.2 Standards for gas explosion protection 548.3 Standards for dust explosion protection and other 54

9 Tolerances 559.1 Electrical parameters 559.2 Mechanical parameters – Normal tolerances 55

10 List of source material 56

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This manual is based on the Explosion Protection Seminar“Planning and Safe Operation of Explosion-protectedElectrical Drives”, Leader/Speakers Dr.-Ing. Lehrmann/ Dipl.-Phys. Seehase/Dipl. Ing. Sattler from “HAUS DER

TECHNIK”, Essen.

Technical processes continually produce explosive atmos-pheres in chemical and petrochemical systems. They arecaused by mixtures of gases, vapours or mists, for exam-ple. Mixtures with dusts, however, such as occur in millsand silos, often also turn out to be explosive. For thesereasons, electrical equipment for explosion hazard areas issubject to special directives and national and internationalstandards. Explosion protection specifies regulations whichhave as their aim the protection of persons and materialsfrom possible risks of explosion.

Integrated explosion protection sets out the occurrence ofexplosion protection procedures in a specified sequence.

In the first place, that means preventing the occurrence ofexplosive atmospheres, preventing the ignition of explosiveatmospheres and limiting the effects of an explosion to an

Preface

insignificant degree. Preventing the occurrence of explosiveatmospheres, also known as primary explosion protection,is also a matter for the system designer and operator.

Which areas, outdoors or in enclosed spaces, are to beconsidered explosive in the sense of the relevant directivesor regulations must be left to the operator to decide or,if doubts exist concerning the determination of explosiveareas, to the supervisory authority responsible. In Directive99/92/EC – ATEX 137 (formerly ATEX 118a), Health andSafety Directive, the responsibilities of the operator of suchsystems are specified. The basis of explosion-protectedproducts is Directive 94/9/EC – ATEX 95 (formerly ATEX100a), (quality directive). The requirements of the productsfor use in explosive areas are defined here.

Electrical machines for use in Zones 1, 2 or 21, 22 may bedesigned as various types of ignition protection, wherebythe aim of each of those types of ignition protection is to

safely prevent ignition of any explosive atmosphere presentwhere the electrical machine is in use.

Explosion-protected equipment is distinguished by thecharacteristic of not igniting any explosive atmospherein the place of use during operation within the permittedparameter limits for the gases occurring (e. g. ambient tem-perature, current, voltage etc.). Since electrical machinesalways contain a potential source of ignition, it is the aim ofthe explosion protection measures to prevent the latter from

becoming an effective source of ignition. Electrical machinesmay become a source of ignition as a result of hot surfaces,electrical discharges and mechanically-produced sparks(from grinding).

The efforts required to prevent danger of ignition are in turndependent on the place of use. Potential explosion areasare divided into zones.

In Zone 0, an explosive atmosphere can occur permanentlyor on a long-lasting basis. Rotating electrical machines arenot used here. Zone 0 is usually inside tanks and systems.

In Zone 1, the explosive atmosphere may be presentoccasionally and short-term. An example of this zone is the

surrounding area of the ventilation hole in tank systems.Equipment used in Zone 1 may be used neither in normaloperation nor on the occurrence of a fault in the ignitionsource.

In Zone 2, only in the case of operational faults can the exi-stence of a short-term explosive atmosphere be expected,e. g. in the case of leaks. The equipment used cannot bea source of ignition in normal operation but it is toleratedin the event of a fault. It is then assumed that there is asufficiently low probability of an explosive atmosphere andan operational fault occurring at the same time. In the caseof danger of explosion from ignitable dusts, there is a similarclassification to Zones 20/21/22.

To ensure explosion protection in the case of rotating elec-trical machines, the following types of ignition protection areconsidered: Increased safety, Flameproof enclosure, Pres-surized enclosure for Zone 1 and type of ignition protection

1 The explosion-protected drive – Introduction

“n” for Zone 2. In dust explosion hazard areas with electricalmachines,”Protection by housing” is a common type ofignition protection. With the Flameproof enclosure “d” typeof protection, ignition inside the housing is possible but thedesign prevents the explosion from being transferred to thesurrounding area. The housing must resist the pressure ofthe explosion and, with ducts, the flames must be pre-

vented from penetrating by using a sparkover-preventiongap. As a further condition, the ignition temperatures of thegases occurring at the assembly site must not be reachedor exceeded on the housing surface. The implementation ofthis type of ignition protection demands effort and expensebecause of the necessary compliance with very low manuf-acturing tolerances.

With the type of ignition protection Pressurized enclosure“p”, the interior of the housing is rinsed under pressurewith an ignition-protection gas below overpressure, pre-venting any ignitable atmosphere from penetrating it. Toguarantee explosion protection, the ignition gas pressuremust be monitored and prohibited surface temperaturesprevented.

If the ignition protection gas supply fails, it must be guaran-teed that all internal ignition sources are no longer present,until the invasion of an exterior atmosphere produces anignitable mixture inside the encapsulation. Because of thecosts of supplying ignition protection gas, this type of igni-tion gas protection is implemented only with machineswhich have an output of more than 1 MW.

In the case of the Increased safety “e” type of ignitionprotection, the surrounding atmosphere may penetrate thehousing interior. To avoid the danger of ignition, there mustalso be no effective ignition sources in the housing interior.

This type of ignition protection can only be implementedwith equipment which produces no sparks in operation. Inorder to design an asynchronous machine of this type ofignition protection, it is fundamentally possible to resort tothe non-explosion-protected standard motor, in the case ofthe inactive electrical parts. In the case of the active parts,

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the reduced permitted temperature rise and requirementsregarding the partial discharges must be taken into account.

The implementation of this type of ignition protection with afrequency-converter-operated drive is carried out at a later

stage of this manual.

Type of ignition protection “nA” (non-sparking device) isbased on the Increased safety “e” type of ignition pro-tection. Because of the lower probability of the presenceof ignitable atmosphere in Zone 2, the requirements are,however, lower. The machine may thus be used at a highertemperature, for example, as there is no necessity for the“safety reduction” of 10 K related to the maximum permis-sible winding temperature according to the thermal class. Inaddition, there is no need to heed the “locked state” fault ormonitor the start-up. Motors of this type of ignition protec-tion must not be started up if there is an ignitable mixture onthe motor’s installation site.

Standard EN 60079 Part 15 provides detailed informationon the relevant requirements. In the sense of Directive

94/9/EC, it is the manufacturer’s responsibility to carry outthe test and put the equipment into circulation. In contrastto the Increased safety “e” type of ignition protection, typeapproval by a notified body is not necessary in this case.

In the case of Increased safety “e” type of ignition protec-tion, the temperature category is a very important factor.Depending on the composition of the possibly ignitableatmosphere there is a temperature category classificationfrom T1–T6. The temperature categories delineate tem-perature ranges into which gases are divided accordingto their ignition temperature. In the case of mixtures, thecomponent with the lowest ignition temperature is definitivefor the classification. The maximum permissible surfacetemperatures for the temperature categories can be foundin Standard EN/IEC 60079-0. Electrical machines of theIncreased safety “e” type of ignition protection are usuallydesigned only up to temperature category T4.

The specifications are based on an estimate by the Explo-sion Protection Certification Authority of PTB Braunschweig.

In the case of mains-operated drives, an estimated dis-tribution is produced across the individual types of ignitionprotection according to Figure 1.1. With frequency-converter-operated drives, the relation between Increa-sed safety “e” and Flameproof enclosure “d” is reversed. The reason for this is the former firm link of motor and

frequency converter with the associated restrictions onthe user and the high cost of the test. The overall costsare lower for a drive of the Flameproof enclosure type of

ignition protection, although distinctly higher costs applyto the motors’ manufacture, in this case. Because ofthe extremely great potential damage in the event of anexplosion, very high priority must be given to the respec-tive safety procedures in the project planning of a drivesystem in explosive areas.

Increased safety “e” Type of ignition protection “n” Flameproof enclosure “d”

Figure 1.1: Distribution of the typesof ignition protectionwith mains-operated drives



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1.1 Summary of the legal principles for explosion protection

Legal principles

Quality requirements Operating requirementsEuropean Law ATEX 95 ATEX 137 94 / 9 / EC 1999 / 92 / EC

Acts Product Safety Act – ProdSG ArbSchG

Health and Safety ActDirectives 11. ProdSV BetrSichV 11th Ordinance to the Product Safety Act Company Safety Directive (Explosion Protection Ordinance)Technical regulations, EN 60079 ff. Explosion protection regulationsregulations andstandards EN 61241 ff. BGR 104, TRBS …

Equipment categories and zones

Equip- Equip- Equip- Certificationment ment Zone ment EPL Definition based on Company Safety Directive obligation group category group Complying with RL94/9/EC Complying with EN 60079-0:2009

For combustible gases, vapours and mist II 1G* 0 II Ga Zone 0 comprises areas in which an explosive atmosphere, yes consisting of a mixture of air and gases, vapours or mist,

exists constantly, long-term or frequently. II 2G 1 II Gb Zone 1 comprises areas in which it can be expected that an yes explosive atmosphere consisting of gases,

vapours or mist occasionally occurs.II 3G 2 II Gc Zone 2 comprises areas in which it is not expected that an no

explosive atmosphere consisting of gases,mist or vapours occurs but when it does occur it is in allprobability only rarely and for a short period.

For explosive dust atmosphere II 1D* 20 III Da Zone 20 comprises areas in which an explosive atmosphere yes

consisting of dust/air mixtures exists constantly,long-term or frequently.

II 2D 21 III Db Zone 21 comprises areas in which it can be expected yes that an explosive atmosphere consisting of dust/air

mixtures occasionally occurs.II 3D 22 III Dc Zone 22 comprises areas in which it is not expected that an no

explosive atmosphere occurs as a result of whirled-up dustbut when it does occur it is in all probability only very rarelyand for a short period.

* not normal for electric motors

Dust explosion protection EN 61241-0 and EN 61241-1

Existence of an explosive Occasionally Rarely or short-term

dust atmosphere Type of dust All types Electrically conductive Electrically non-conductive

Zone 21 22 Equipment group II Equipment category 2D 3D 3D Type of protection IP 65 IP 55 Temperature Housing temperature max. 125 °C Certificate EC type-examination Manufacturer’s EC Declaration of Conformity certificate

Coding tD A21 IP 65 T125 °C tD A22 IP 65 T125 °C tD A22 IP 55 T125 °C

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1.2 Summary of the legal principles for explosion protection

General requirements EN 60079-0:2009(gas and dust)

Flameproof enclosure “d” EN 60079-1:2007

Type of ignition protection – Flameproof enclosure “d”

Increased safety “e” EN 60079-7:2007 Type of ignition protection – Increased safety “e”

Type of ignition protection “n” EN 60079-15:2010 Type of ignition protection “n”

Pressurized enclosure “p” EN 60079-2:2007

Type of ignition protection – Pressurized enclosure “p”

Powder filling “q” EN 60079-5:2007 Type of ignition protection – Powder filling “q”

Oil immersion “o” prEN 60079-6:2007 Device of protection – Oil immersion “o”

Intrinsic safety “ia/ib” EN 60079-11:2012

Device of protection – Intrinsic safety “i”

Encapsulation “m” EN 60079-18:2009 Type of ignition protection – Encapsulation “m”

Dust explosion protection EN 60079-0:2009 and EN 60079-31:2009

Existence of an explosive Occasionally Rarely or short-term

dust atmosphere Type of dust All types Electrically conductive Electrically non-conductive

Zone 21 22 Complying withEquipment groupRL94 / 9/ EC II

Complying withEquipment groupEN 60079-0:2009 IIIC IIIC IIIB

Equipment category 2D 3D 3D EPL n. EN 60079-0:2009 Db Db, Dc Db, Dc Type of protection IP 65 IP 65 IP 55 Temperature Housing temperature max. 125 °C Certificate EC type-examination Manufacturer’s EC Declaration of Conformity certificate

Coding complying with RL94 / 9 / EC II 2D II 3D II 3D

Coding complying with Ex t IIIC T125 °C Db Ex t IIIC T125 °C Dc Ex t IIIB T125 °C Dc EN 60079-0 / EN (Alternative: (Alternative: (Alternative:60079-31 Ex tb IIIC T125 °C) Ex tc IIIC T125 °C) Ex tc IIIB T125 °C)

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1.3 Explanation of the general requirements, the types of ignition protectionand areas of application

1.3.1 General requirements (gas and dust)

Technical explanation

EN 60079-0:2009 ( VDE 0170-1)– Distinction Group I (mining), II (gas) and III (dust)– Requirements transferred from dust areas EN 61241-0– Newly-introduced groups for dust (IIIA, IIIB and IIIC)– Explosion groups for Group II (IIA,IIB and IIC)– Introduction of Equipment Protection Level (EPL)– Ambient temperature range -20 °C to +40 °C– Maximum operating temperature (maximum ambient

temperature + intrinsic heating + external heat sources)– Maximum surface temperature

(temperature categories T1…T6)– Mechanical stability– Opening periods (capacitors and hot fitted parts)– Circulating currents– Seal attachment

– Equipment with electromagnetic and ultrasound energy– Requirements of non-metallic housings and housing com-ponents

– Operating instructions and coding– Tests

Subdivision of Equipment Group IIComplying with EN 60079-0:2006, because of theirparticular ignitability in Flameproof enclosure “d”and Intrinsic safety “i” types of ignition protection, gasesand vapours have been divided into three explosiongroups, IIA, IIB and IIC. The danger increases betweenExplosion Groups IIA and IIC. (The higher explosion group,e. g. IIC includes the lower ones, IIB and IIA).From EN 60079-0:2009, Coding II is replaced for all gasprotection types by the specifications IIA, IIB and IIC(so now also … Ex e IIC T3 or … Ex nA IIC T3)– IIA, typical gas is propane

– IIB, typical gas is ethylene– IIC, typical gas is hydrogen

Temperature categories

EN 60079-0 Explosion Groups IIA; IIB; IICMedium’s ignition temperature Temperature categorie Permitted equipment surface temperatureat limit temperature including 40 °C ambient temperature (limit temperature)over 450 °C T1 450 °C300 – 450 °C T2 300 °C200 – 300 °C T3 200 °C

135 – 200 °C T4 135 °C100 – 135 °C T5 100 °C85 – 100 °C T6 85 °C

Subdivision of Equipment Group IIIElectrical equipment in Group III is further subdividedaccording to the properties of the explosive atmospherefor which it is intended. The potential danger of dust in-creases with the operation of electrical equipment betweenIIIA and IIIC. Group IIIC equipment includes suitability forgroups IIIA and IIIB.– IIIA, combustible lint– IIIB, combustible, electrically non-conductive dust– IIIC, combustible, electrically conductive dust

Equipment Protection Level(EPL, definition complying with EN 60079-10-2)

Gas explosion protection:EPL Ga: Device with “very high” protection level for use in

gas explosion hazard areas, in which there is nodanger of ignition in normal operation and withforeseeable or rare faults/malfunctions.

EPL Gb: Device with “high” level of protection for use in gasexplosion hazard areas in which there is no dangerof ignition in normal operation or in the case offoreseeable faults/malfunctions.

EPL Gc: Device with “extended” protection level for usein gas explosion hazard areas, in which there isno danger of ignition during normal operationand which have some additional safety measureswhich ensure that there is no danger of ignition inthe case of normal foreseeable faults in the device.

Dust explosion protection:EPL Da: Device with “very high” level of protection for use

in combustible dust atmospheres in which thereis no danger of ignition in normal operation or withforeseeable or rare errors/malfunctions.

EPL Db: Device with “high” level of protection for use incombustible dust atmospheres, in which there isno danger of ignition in normal operation or withforeseeable errors/malfunctions.

EPL Dc: Device with “extended” level of protection for usein combustible dust atmospheres, in which thereis no danger of ignition in normal operation andwhich have some additional safety measureswhich guarantee that there is no danger of ignitionwith faults in the device that are normally to beexpected.



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Definition of protection principles– Explosive mixtures can penetrate the equipment and

ignite. The explosion is not transferred to the explosiveatmosphere surrounding the equipment. (Ex d)

– The equipment has an encasing which prevents the ex-plosive mixture from penetrating and coming into contactwith an ignition source. (Ex m, Ex o)

– Explosive mixtures can penetrate the equipment, butmust not ignite in normal operation. Sparks and hightemperatures above the ignition temperature of the gasconcerned must be prevented. (Ex nA)

– Explosive mixtures can penetrate the equipment, butmust not ignite even in case of a foreseeable fault. Sparks

and high temperatures above the ignition temperature ofthe gas concerned must be prevented in normal operati-on and in case of a foreseeable equipment fault. (Ex e)

– Explosive mixtures can penetrate the equipment, butmust not ignite. The energy in the circuits is limited.Sparks and high temperatures may occur to a limited

degree, but without igniting gases of the explosion groupfor which the equipment is certified. (Ex i)– Explosive mixtures must not penetrate the equipment in

critical amounts. The only decisive factor is thus compli-ance with the maximum temperature on the outer surface(Zones 21, 22: Ex t)

Explosion hazard Equipment group and Equipment group andarea complying with category complying with Equipment Protection Level (EPL)Directive 94 / 9 / EC Directive 94 / 9 / EC complying with 60079-0:2009Zone 2 II 3G II GcZone 1 II 2G II Gb

Zone 0 II 1G II GaZone 22 II 3D III DcZone 21 II 2D III DbZone 20 II 1D III DaMining (high safety level) I M2 I MbMining (very high safety level) I M1 I Ma

1.3.2 Types of ignition protection1.3.2.1 Type of ignition protection – Flameproof enclosure “d”

Design regulations: EN 60079-1:2007 (VDE 0170-5)

Definition/protection principle: Type of protection with which the components capable ofigniting an explosive atmosphere are arranged inside a hous-ing, which sustains the pressure inside when an explosivemixture explodes and prevents the explosion from beingtransferred to the explosive atmospheresurrounding the housing.– Heeding the explosion group– Pressure-resistant housing– Conforming to the required gap widths and lengths– Terminal box Flameproof enclosure “d”

or in Increased safety “e”– Temperature of outer surface must be lower than

the ignition temperature of the surrounding gasses

– An explosion may occur in the interior. The housing mustresist this explosion and no flames or potentially ignitablegasses must reach the outside through the gap

Tests:– Reference pressure and resistance to pressure– Sparkover– Leak test for gap sealed in place

Areas of application:Equipment Zones 1 and 2,Categories 2G and 3G (Gb, Gc)

1.3.2.2 Type of ignition protection – Increased safety “e”


Definition/protection principle: Type of ignition protection, in which additional measures aretaken in order to prevent the possibility of the occurrence ofprohibited high temperatures and the production of sparksor arcs in use according to specifications or in specifiedunusual conditions.– Prevention of sparks and other ignition sources– Housing at least IP 54, if bare live parts are present in the

interior– Housing at least IP 44, if all live parts in the interior are

insulated– Temperatures of the exterior and interior surfaces must

be lower than the ignition temperature both in normaloperation and in the event of a fault (locking the motor).

– Taking creepage distances and clearances into account– Paying particular attention to the insulating materials and

seals

– Protective equipment (temperature monitor and/orovercurrent switch with I

A /I

N-t

E time characteristic curve)

essential for the user– Frequency-converter operation – see Chapter III

Tests:– Insulation test– Temperature measurement in the case of specific faults– Additional tests for specific equipment

(TMS full protection)




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1.3.2.4 Type of ignition protection – Pressurized enclosure “p”Design regulations: EN 60079-2:2007 (VDE 0170-3)

Definition/protection principle: Type of ignition protection for electrical equipment with whichpenetration of the housing by a surrounding atmosphereis prevented by an ignition gas being held under primarypressure in its interior against the surrounding atmosphere.

The overpressure is maintained with or without ignition gasrinsing.– Housing at least IP 4X – Monitoring equipment– Gas outlet– Containment system

Tests:– Pre-flush time– Leakage losses– Overpressure test (1.5 x P)– Minimum flow


1.3.2.5 Type of ignition protection – Powder filling “q“

Other types of gas ignition protection not relevant to electric motors,without detailed consideration:


Definition/protection principle: Type of ignition protection, with which the parts of a pieceof equipment, which can become an active ignition source,are fixed in their position and completely surrounded byfilling material, to prevent ignition of an external explosiveatmosphere.

– Filling material– Locks– Clearances– Housing at least IP 54– Energy store

Tests:– Pressure test (50 kPa)– Filling material insulating property– Inflammability of plastics

Areas of application:

Category 2G (Gb)Capacitors, primary cells, transformers,ballast control gears and sensors

1.3.2.6 Type of ignition protection – Oil immersion “o”


Definition/protection principle: Type of ignition protection, with which the piece of electricalequipment or its parts is/are immersed in a fluid encapsu-lation, in such a way that an explosion hazard atmospherewhich may be located above the liquid or outside theencapsulation cannot be ignited.– Protective liquid– Minimum fill level– Type of protection IP 66– Fill-level monitor– Energy store

Tests:– Overpressure test– Temperatures

Areas of application:Category 2G (Gb)

Transformers, switchgears and starting resistors

1.3.2.3 Type of ignition protection – “n” (non sparking)


Definition/protection principle: Type of ignition protection of electrical equipment with which

it is possible to prevent the equipment from being in a posi-tion to ignite a surrounding explosive atmosphere, in normaloperation. The design guarantees minimisation of the risk ofoccurrence of arcs or sparks which can cause a danger ofignition during normal use.– Prevention of sparks and other ignition sources– Housing at least IP 54– Taking creepage distances and clearances into account– Paying particular attention to the insulating materials and

seals. In normal operation, exterior and interior surfacetemperatures must be lower than the ignition temperature

Tests:– Insulation test– Temperature measurement– Additional tests for specific equipment (frequency converter operation)

Areas of application:Equipment Zone 2, Category 3G (Gc)



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1.3.2.7 Type of ignition protection – Intrinsic safety “ia/ib”


Definition/protection principle:Intrinsically safe circuit – a circuit, in which no spark or no

thermal effect occurs, which, under the test conditionsspecified in this standard (comprising normal operation andspecific fault conditions), can cause ignition of a certainexplosive atmosphere.– Separation distances– Insulations– Structural components

Tests:– Spark test

– Insulation test– Spark test with small components– Consideration of output

Areas of application:Categories 1G, 2G and 3G, 1D, 2D and 3DEPL Ga, Gb and Gc, measurement andcontrol electronics, sensors and PC interfaces

1.3.2.8 Type of ignition protection – Encapsulation “m”

Design regulations: EN 60079-18:2009 (VDE 0170/0171-9)

Definition/protection principle: Type of ignition protection, with which the parts which canignite an explosive atmosphere through sparking or heatingup are embedded in a sealing compound in such a way thatan explosive atmosphere cannot be ignited under operatingand installation conditions.– Sealing compound– Level of protection– Clearances and cavities

Test:– Water intake– Resistance to heat and cold– Thermal cycle test– Insulation test

Areas of application:Categories 1G (ma) and 2G (mb)EPL Ga and GbSwitch gears for low output, sensors, solenoids,signalling and command devices

1.4 Summary of types of ignition protection for dust-explosion protection

General requirements EN 60079-0:2009

Protection by housing “tD”(“tx IIIY T ---°C Dx”) EN 60079-31:2009

Pressurized enclosure “pD” EN 61241-4:2006(“p IIIY Dx”) (EN 60079-2:2007)

Intrinsic safety “iD” EN 60079-11:2012(“ix IIIY Dx”)

Encapsulation “mD” EN 60079-18:2009(“mx IIIY Dx”)

x = EPL, Y = Explosion group

Example of labelling for protection by enclosure: II 2D Ex tb IIIC Db



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1.4.1 Type of ignition protection – Protection by housing “tD”

Explanation of types of ignition protection and areas of application:

Design regulations: EN 61241-1:2004 (VDE 0170-15-1)

Protection principle: The temperatures of surfaces on which dust can accumu-late or which can come into contact with a dust cloud arekept below the temperatures specified in this standard.

All the parts with electrical sparks or temperatures abovethe limit values specified in EN 61241-1 are enclosed ina housing, which prevents the penetration of dust in anappropriate way.Process A: Compliance with specified types of protectionProcess B: Minimum gap lengths and maximum gap widths– Prevention of sparks and other ignition sources– Minimum types of housing protection with Process A: use in Zones 21 and 22 with conductive dust: IP 65 use in Zone 22 with non-conductive dust: IP 55

– Taking creepage distances and clearances into account

– Paying particular attention to the insulating materials andseals. In normal operation, exterior surface temperaturesmust be lower than the limit values.

Tests:– IP protection type test– Temperature measurements

Areas of application:Equipment Zones 21 and 22,Categories 2D and 3D (Db, Dc)

1.4.2 Type of ignition protection – Protection by housing “tx IIIY Dx”

Design regulations: EN 60079-31:2009 (VDE 0170-15-1)

Protection principle:Dangerous housings are enclosed by the housing which isnot liable to malfunction. Evidence of the maximum surfacetemperature according to category.Minimum type of protection IP 5X/6X (EN 60529)New: Pressure test with an overpressure as follows: – 4 kPa with devices with “ta” level of protection

– 2 kPa with devices with “tb” or “tc”level of protection before the dust test

Limitation of the 10 kA for EPL Da short-circuit current foracceptance

Temperature limitation depending on EPLDetermining the surface temperature for EPL Da, with alayer of dust of at least 500 mm on all accessible surfaces.

Tests:– IP protection type test– Ageing resistance of polymers used on the device– Impact test– Leak tightness– Thermal test with overload or fault conditions

Subdivision of groups:– IIIA, combustible lints– IIIB, non-conductive dust– IIIC, conductive dust

Protection against ingress of dust according totable 1, EN 60079-31:2009

Group Level of protection Type of protection/housingIII A (fibers) ta IP 6X

tb IP 5X tc IP 5X III B (non-conductive dusts) ta IP 6X tb IP 6X tc IP 5X

III C (conductive dusts) ta IP 6Xtb IP 6X

tc IP 6X



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1.4.3 Type of ignition protection – Pressurized enclosure “pD”

The other dust types of ignition protection, which are not relevant to electric motors:


EN 60079-2:2007 (“p IIIY Dx”)

Definition/protection principle: Type of ignition protection for electrical equipment withwhich penetration of the housing by a surrounding atmos-phere is prevented by an ignition protection gas being heldunder overpressure (> 50 Pa) in its interior against the sur-rounding atmosphere. The overpressure is maintained withor without ignition gas rinsing.– Housing at least IP 4X – Monitoring equipment– Gas outlet– Containment system

Tests:– Pre-flush time– Tightness– Overpressure test (1.5 x P; > 200 Pa)– Impact test

Areas of application:Switchgears, transformers,complex equipment and cabinets

1.4.4 Type of ignition protection – Intrinsic safety “iD”

Design regulations:EN 60079-11:2012 (VDE 0170-7) (“ix IIIY Dx”)

Definition/protection principle:Limitation of the electric power (voltage, current, inductanceand capacity), including the surface temperatures, so thatno ignition occurs of a dust-air mixture as a result of sparksor thermal effects with intrinsically safe devices in normaloperation and with specific fault conditions complying withEN 60079-11:2007.– Separation distances– 2/3 capacity

– Non-susceptance to faults

Tests:– Spark test– Insulation test– Spark test with small components– Consideration of output– No IP required

Areas of application:MCR equipment, sensor,

mobile measuring equipment

1.4.5 Type of ignition protection – Encapsulation “mD”

Design regulations:EN 60079-18:2009 (VDE 0170/0171-9) (“mx IIIY Dx”)

Definition/protection principle: Type of ignition protection, with which the parts are embed-ded in sealing compound in such a way that the explosiveatmosphere cannot be ignited under operating and installa-tion conditions.– Minimum requirements of sealing compound (TI value)

– Minimum sealing compound thickness(3 mm “ma” and 1 mm “mb”)

– Faults analysis in sealing compound– Level of protection– Clearances and cavities– Rated values

Test:– Water intake– Evidence of maximum surface temperature– Resistance to heat and cold– Thermal cycle test– Insulation test

Areas of application:Switchgears for low output, commandand signalling devices, solenoids, ultrasound sensors



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1.5 Markings complying with different editions of the standardCategory 3 motors carry only the CE marking on their ratingplate. The NB ID number for quality assurance in accord-ance with Directive 94/9 EC is not to be specified on suchequipment.

One of the changes in EN 60079-0:2009 (DIN EN 60079-0:2010) compared to previous editions of the standard isthe introduction of Equipment Protection Levels (EPL). Inthis connection, the previous marking of explosion-pro-tected motors is also changed.

Labelling complying Old designations Designation complying Designation complying with with directive 94 / 9 / EC withEU No. Group/ EN 60079-0:2009

NB Category/ G (gas) or (EN 50014 ff., and EN 60079-0:2006 and Alternative D(dust) EN 50281,…) EN 61241-0:2004 With EPL designation EN 50019 EN 60079-7 EN 60079-7 EN 60079-7

0102 II 2G EEx e II T2, T3 or Ex e II T2, T3 or T4 Ex e IIC T3 Gb Ex eb IIC T3 T4EN 50021, IEC 79-15 EN 60079-15 EN 60079-15 EN 60079-15

II 3G EEx nA II T2, T3 or Ex nA II T2, T3 or T4 Ex nA IIC T3 Gc Ex nAc IIC T3 T4

EN 50281-1-1 EN 61241-1 EN 60079-31 EN 60079-31 0102 II 2D IP 65 T125 °C Ex tD A21 IP 65 T125 °C Ex tb IIIC T125 °C Db Ex tb IIIC T125 °C EN 50281-1-1 EN 61241-1 EN 60079-31 EN 60079-31 II 3D IP 55 T125 °C Ex tD A22 IP 55 T125 °C Ex tc IIIB T125 °C Dc Ex tc IIIB T125 °C (IP 65 conductive (IP 65 conductive (Ex tc IIIC T125 °C Dc) (Ex tc IIIC T125 °C) dust) dust)

Combination of gas or dust

II 2D IP 65 T125 °C Ex tD A21 IP 65 T125 °C Ex tb IIIC T125 °C Db Ex tb IIIC T125 °C

0102 EEx e II T2, T3 orII 2G T4 Ex e II T2, T3 or T4 Ex e IIC T3 Gb Ex eb IIC T3

0102 II 3D IP 55 T125 °C Ex tD A22 IP 55 T125 °C Ex tc IIIB T125 °C Dc Ex tc IIIB T125 °C

(IP 65 conductive dust) (IP 65 conductive dust) (Ex tc IIIC T125 °C Dc) (Ex tc IIIC T125 °C) II 2G EEx e II T2, T3 Ex e II T2, T3 or T4 Ex e IIC T3 Gb Ex eb IIC T3 or T4

0102 II 2D IP 65 T125 °C Ex tD A21 IP 65 T125 °C Ex tb IIIC T125 °C Db Ex tb IIIC T125 °C EEx nA II T2, T3

II 3G or T4 Ex nA II T2, T3 or T4 Ex nA IIC T3 Gc Ex nAc IIC T3

II 3D IP 55 T125 °C Ex tD A22 IP 55 T125 °C Ex tc IIIB T125 °C Dc Ex tc IIIB T125 °C (IP 65 conductive dust) (IP 65 conductive dust) (Ex tc IIIC T125 °C Dc) (Ex tc IIIC T125 °C) II 3G Ex nA II T2, T3 Ex nA II T2, T3 or T4 Ex nA IIC T3 Gc Ex nAc IIC T3

or T4

[If a maximum surface temperature is specified: Zone 2 (gas): Total surface including rotors and windings; in the case ofZones 21 and 22 (dust): external surface (housing and shaft)]

Notified bodyID number 0102… Physikalisch-Technische Bundesanstalt Braunschweig 0637… IBExU Institut für Sicherheitstechnik GmbH, Freiberg 0158… DEKRA EXAM GmbH

The number of the notified body which completed certification complying with directive 94/9/EC must be quoted as theID number. This is not always the same as in the EC type-examination certificate.

In addition to specifications in accordance with the ATEXdirective (e.g. Ex II 2G for motors for increased safety - typeof ignition protection “e”), the rating plate will in future alsoindicate the equipment protection level (e.g. Exe IIC T3 Gb).

The standard also permits an alternative (abridged) markingalongside the actual EPL marking under certain circum-stances. This alternative is not used by VEM motors.




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Examples of rating plates:

IP kg

155

55 175

Th.Kl./Th.cl./Cl.th.

Ex tc IIIB T125°C Dc

II 3DVEM motors GmbH

D 38855 WernigerodeMade in Germany

DE

NE

cm3

Fett/Grease/Graisse

hcm

3

V

3~Mot.Nr./N /M.o

Hz A kWcos

193015 / 0001 H K21R 180 M2 Ex 3D TPM VIK HW

16

50 1,20,91 19,5 2655

min /r.p.m./rev/m-1

Umrichterbetrieb/Converterfeeding/Alim.par convertisseur

02/2013IM B3 IEC / EN 60034-1

500 22,00,90 31,0 2940Y 50

22,00,90 31,0 294050

100 3,00,90 22,5 56010

Y

Y

Y500

6310 C3 DIN625

6310 C3 DIN625

Motor for use in Zone 22 Motor with double marking foruse in Zones 2 and 22

A number of customers (and perhaps also manufacturers)believe that an obligation to attach markings according to

the new standard came into force already on 01/06/2012,the date on which the old standard expired. This interpre-tation, however, is incorrect. The only document whichdeclares the conformity of our explosion-protected motorswith ATEX regulations is the EC Declaration of Conformity.

The explosion protection section of the PTB Braunschweigwebsite also contains documents which address this situ-ation (Commentary on the meaning of the requirementof EU Directive 94/9/EC (ATEX), Annex II, Part A; Impactof the replacement of existing standards with newharmonised standards; Issuing of EC Declarations ofConformity in compliance with Directive 94/9/EC afterpublication of a new edition of a standard).

Second rating plate enclosed separately with explo-

sion-protected motorsIn some cases, customers may also request a secondseparate rating plate to be enclosed with explosion-pro-tected motors. This is often the case where the rating plateattached to the motor is no longer visible after the motoris installed in a machine or plant. The current standards,however, do not permit a complete second rating plate tobe enclosed separately with a delivery.

Rules for the marking of explosion-protected products arelaid down in DIN EN 60079-0, chapter 29.

The basic requirement reads: “It is imperative that the fol-lowing system of markings only be used on electrical equip-

ment or explosion-protected components which complywith the valid standards applicable for the type of ignition

protection concerned as listed in Section 1.”

This means that it is not permissible to attach an explosionprotection marking in accordance with DIN EN 60079-0 tocomponents or products which do not conform to the re-levant standards and are thus also not certified accordinglyby the manufacturer or notified body.

DIN EN 60079-0, chapter 29.1 also contains stipula-tions with regard to the location of the marking:“The electrical equipment must bear a clearly legible markon the outside of the housing of the main component andthis mark must be legible before installation of the equip-ment.”

This means that the component of a machine/plant whichbears explosion protection marking is considered the maincomponent of the ATEX-certified equipment.

It is consequently not permissible to supply a second ratingplate with explosion protection marking and parameters forattachment at some other location separate from the motor.

As an alternative, for example where the main motor ratingplate is not clearly legible after installation, it is possibleto provide a second or additional motor information platewithout explosion protection marking (see examples below,with specification of the motor number and all electricalparameters).

tE s

IP

VEM motors GmbH

D 38855 WernigerodeMade in Germany0637

II 2G Exe IIC T2/T3 Gb

II 2D Ex tb IIIC T125 °C Db

65

kg

V

186675 / 0001

PTB 08 ATEX 3038/05

K11R 160 L4 Exe II T2/T3 2D VIK HW

IBExU 09 ATEX 1065

7,2 10 15501.02.2013

IM B35

Beschein./Certif.2G:

Prüfung/Test/Essai

Hz

3~Mot.Nr./N /M.o

A kWmin /r.p.m./rev/m-1

I /I A N

cos

Th.Kl./Th.cl./Cl.th.

DE

NE

cm3

Fett/Grease/Graisse

h6310 2RS C3 DIN625

6309 2RS C3 DIN625 cm3

Beschein./Certif.2D:

136

400/690 D/Y 50 0,86 26,0/15,1 1470 13,5

IEC / EN 60034-1

VEM motors GmbH

D 38855 WernigerodeMade in Germany

1

186675 / 0001K11R 160 L4 Exe II T2/T3 2D VIK HW

136

13,5 0,86

D/Y

02/2013

400/690

IEC / EN 60034-1

26,0/15,1

1470 50

155 65

3~Mot.Nr./No

Typ/Type

V

Hz

A

kW cos

min /r.p.m.-1

IP kgTh.Kl./Th.cl.

DE

NE

cm3

Fett/Grease

h6310 2RS C3 DIN625

cm3

Ex-Kennzeichnung siehe Motorhaupttypenschild/Ex-identification see main name plate

6309 2RS C3 DIN625

Motor for use in Zones 1 and 21 Corresponding additional rating platewithout Ex marking



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I P p r o t e c t i o n

E n d s h i e l d

D - s i d e

A n t i - f r i c t i o n

b e a r i n g

C a b l e a n d

w i r e i n l e t s

C l e a r a n c e s a n d

c r e e p a g e d i s t a n c e s

T e r m i n a l s y s t e m

E n d

s h i e l d

N - s

i d e

M o t o r s h a f t

R o t o r

F a n t e s t

D i s t a n c e b e t w e

e n

m o v i n g p a r t s

I m p a c

t t e s t

R o

t o r d e s i g n / o b s e r v i n g

m i n i m u m a i r g a p

E a r t h i n g

1.6 Electric motors – Mechanical structure and main focuses of designfor conformity with explosion protection

F a n

F a n c o v e r

A n t i - f r i c t i o n

b e a r i n g

M o t o r h o u s i n g

A i r - c o n d i t i o n e d

s t o r a g e p l a s t i c s t e s t

M o t o r f e e t

C o r e

w o u n d



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Standard EN 60079-0 is the basis of the mechanical designof all electrical machines for use in explosion-protectedareas. With the Increased safety “e” (EN 60079-7) type ofignition protection, the main focuses are on the followingareas, which have to be subjected to suitable tests:

Cable and wiring inlet:Performance of tensile tests and increase in elastomerhardness: EN 60079-0

Material couplings: Avoiding formation of abrasion and impact sparks

Clearance and creepage distances:Observing the clearance and creepage distances complyingwith EN 60079-7 for avoiding ignitable electrical dischargesand sparkovers

Distance between moving parts: Avoiding mechanical grinding during operation. In thecase of asynchronous machines, for example, the air gap

minimum value between stator and rotor must be observed,complying with EN 60079-7.

Impact test:Guaranteeing adequate protection against mechanicaldamage

Fan test: Testing the fan’s mechanical stability

Plastics test: Testing the heat and cold resistance of the plastics used

and testing the seals’ heat resistance. In the case of plasticsurfaces with a surface greater than that specified inEN 60079-0, depending on the explosion group, it isnecessary to deal with the problem of electrostatic loads.

IP protection:

Testing the equipment’s type of IP protection against solidbodies and liquids. If it has been established that theabove-mentioned points have been satisfied in the sense ofthe requirements of the standard, a mechanical test reportis compiled by the test authority which forms the basis ofthe EC type-examination certificate. An inspection of theoperating instructions is also part of that, as are documentswhich describe the series’ design. Later modifications bythe manufacturer are permitted only after consultation withthe test authority and amendments or new EC type-exami-nation certificates may be necessary.

Winding design and electrothermal test:No part of the electrical equipment must become warmerthan the temperature resistance permitted by the materials

used. In addition, no surface of a part of the equipment,including the interior parts, which could come into contactwith the atmosphere depending on the type of ignitionprotection, must become warmer than the highest surfacetemperatures complying with IEC 60079-0.

In the case of motors of the Increased safety “e” typeof ignition protection, the limit temperature of insulatedwindings must not exceed the values corresponding toEN-60079-7 (see table), on which the insulating materials’thermal resistance is based.

Limit temperatures for insulated winding

Temperature Heat category of insulations complyingmeasurement process with IEC 60085 (see Note 2)

(see Note 1) 105 (A) 120 (E) 130 (B) 155 (F) 180 (H) °C °C °C °C °C 1 Limit temperature

at rated operation a) single-layer insulated windings Resistance or 95 110 120 130 155 temperature

b) other insulated windings Resistance 90 105 110 130 155 temperature 80 95 100 115 135 2 Limit temperature at end of t

Etime (see Note 3) Resistance 160 175 185 210 235

Note 1: Measurement by thermometer is permitted only if the measurement is not possible by modifying the

resistance. In this context “thermometer” meansthe same as in IEC 60034-1 (for example, a bulbthermometer, a non-embedded thermocouple ora resistance temperature detector (RTD), which isused at the points which are accessible to a normalbulb thermometer).

Note 2: It is accepted as a provisional measurement untilvalues have been stipulated; the higher insulatingmaterial heat categories designated in figures inIEC 60085 are regarded as applicable to the limittemperatures specified in Category 180 (H).

Note 3: These values are composed of the ambient tem-perature, the winding overtemperature in measure-ment mode and the temperature increase duringthe t

E time.



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In addition to the mechanical design, the electrothermaldesign and test is a very important step on the way to ECtype-examination certificate for an explosion-protectedelectrical machine. The data acquired during the motors’test form the basis of the data sheet for the EC type-exami-nation certificate and guarantee safe operation of the motor

if they are observed. The electrothermal test comprises the followingitems:– Inspection as to whether the winding design satisfies

the criteria of the Increased safety “e” ignition protection type– Determining/verifying the machine’s measurement

data– Determining the continuous duty temperature rise

During the performance of the temperature rise measure-ment, the DUT is given the prescribed mechanical load andthe electrical power input, the mechanical force delivered,and current, voltage, speed and torque are measured andautomatically logged during the experiment. The measure-

ment may be terminated if the temperatures measured dur-ing operation on the housing change by less than 2 K perhour (thermal equilibrium complying with EN 60034). Thestator winding temperature is calculated by the tempera-ture-dependent resistance change from a winding resist-ance measurement before the experiment, in the case of acold machine, and after the thermal equilibrium has beenreached, in the case of a machine at operating temperature.

The rotor temperature is measured after the experiment bya sensor on the end ring, introduced through a hole in theend shield.

Temperature measurement The temperature on the housing is measured by thermo-couples which are press-fitted in small holes, to guaranteethe best possible heat transfer. In addition, temperaturesare measured on elastomer seals, on cable entry and leadintersections, as well as on existing add-on componen-

ts. There must be a guarantee that both the temperaturecategory’s limit temperature, for which the motor is to becertified, and also the permitted continuous use tempe-ratures, for the plastics and add-on components used,are not exceeded. With the Increased safety “e” types ofignition protection, temperature measurement of the statorand the rotor types of ignition protection is necessary forZone 1 and “nA” is necessary for Zone 2. In the case of theFlameproof enclosure “d” and Protection by housing (dust)types of ignition protection, only temperature rise of theexterior surfaces must be tested.

A further important measurement is the determination oftemperature rise in the locked state (only Increased safety“e” type of ignition protection).

For example, Figure 1.2 shows the temperature characte-ristics determined during a temperature rise test on thehousing. When the “thermal equilibrium” is reached, i. e.temperature rise less than 2 kph, the measurement is ter-minated. To evaluate the measurement taking into accountthe limit temperatures of the elastomers used, the highesttemperature occurring after the motor is switched off mustbe taken into account for each such measurement point(e. g. seal).

Figure 1.2: Example of housing temperature characteristics during the test

10 °C

20 °C

30 °C

40 °C

50 °C

60 °C

70 °C

°C09:30 10:42 11:54 13:06 14:18 15:30 16:42Time

O v e r t e m p e r a t u r e s a n d c o o l a n t t e m p e r a t u r e

Highest temperature rises

Room temperature

Side of housing

Cable and wiring inlet

A-side of bearing

Housing eyelet

B-side of bearing

Lead intersection



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Inspecting the machine protection/determining thet

E time and the starting/rated current relation

This fault may, for example, occur if a machine is locked.Characteristic of this is the motor current reaching a multi-ple of the measured current (e. g., seven times) and themachine heating up intensely within the shortest possible

period of time. Without motor protection, the permittedlimit temperatures would have been exceeded within a fewseconds. For that reason, the machine must be protectedby a time-controlled overcurrent protection device (motorprotection switch) or PTC thermistor located in the winding,against prohibited temperature rises as a result of overload.

For measuring the temperature rise in the machine whilethe brake is fully applied, the rotor is prepared with thermo-couples at intervals along its length and the locked motorswitched on for a specified time, for example, 15 s.

The rotor’s temperature characteristics are shown by athermograph and the stator’s winding temperature is deter-mined by the increased winding resistance after shutdown.

The locking attempt is carried out with both phase sequen-

ces, whereby measurable differences in the temperaturerise are produced with bevelled rotor bars in the rotor. Therotating field with the highest rises in temperature is used forthe rest of the evaluation.

In the case of machines of the Flameproof enclosure “d”protection type, locking does not have to be taken into ac-count, as it is assumed that no incendive temperature risesoccur with motor protection corresponding to the latestdate of technology, because of the high thermal capacity ofthe stator core and the housing on its surface.

With type of ignition protection “nA” for Zone 2, the fault,that is the locked state, does not have to be taken intoaccount either.

Time tE

Time tE is a very important value in the EC type-examination

certificate data for the Increased safety “e” type of ignitionprotection. This value states the latest time after which theovercurrent protection device (motor protection switch)must switch off the motor in the locked state.

In order to determine this, the continuous duty temperaturerise and the temperature rise speed are required for statorand rotor in the locked state. On the basis of the continu-ous operating temperature and the maximum permittedtemperatures for rotor and stator, the maximum permittedtemperature increase is determined in the locked state andthe maximum duration for the locked state is calculated bythe temperature rise speed, for both rotating field directions.

The smaller of the two numerical values produces the tE

time minus a safety deduction of at least 5 %. If the machi-

ne is protected by a device for direct temperature monito-ring, e. g. PTC thermistor, with the machine locked it mustbe proved, by means of an overload attempt and shutdownattempt, that no prohibited temperatures occur, also in thecase of a fault. The t

A time is then part of the EC type-exa-

mination certificate instead of the tE time and the I

A /I

N is not

specified. The maximum permitted temperature rises aregiven in the standards EN 60079-0 (temperature categories)and EN 60034 (winding insulation thermal classes).

Figure 1.3: Definition of tE time

Hours Seconds

tE Time

Prohibited temperature range

Permitted temperature range in the event of a fault

Continuous duty temperature range



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1.7 High-voltage tests on windings under gas

These tests are necessary, if the following criteria apply:– The machine is a high-voltage machine

(rated voltage > 1kV).– An ignition danger assessment complying with

EN 60079-7 Table G.1 has produced an ignitiondanger factor > 6.

The high-voltage test is made up of an AC test and animpulse voltage test. There the windings are individuallytested, with the unused phases and the stator core beingearthed. The DUT is in an explosive mixture. Hydrogen isused for Explosion Group IIC, ethylene for IIB and propanefor IIA. The minimum ignition energies increase from Explo-sion Group IIC to IIA. The test is considered to be passed ifthere is no ignition in the test of two winding phases in the

AC and impulse voltage tests.

C

Figure 1.4: Impulse voltage test on a winding modelunder gas (photo: PTB Braunschweig)

1.8 Installation and electrical connection

The safety instructions supplied with the motor must beheeded for assembly and commissioning.

Assembly tasks must only be carried out by specialist per-sonnel, who, on the basis of their specialist training, expe-rience and instruction received, have adequate knowledgeof the following:– Safety instructions– Accident prevention regulations– Guidelines and generally-accepted regulations

of technology (e. g. VDE regulations and standards).

The specialist personnel must be able to assess the tasksassigned to them and recognise and prevent possible dan-gers. It must be given the authority by the person respon-sible for the machine’s safety to perform the required tasksand activities. In Germany, installing electrical machines inexplosion hazard areas requires compliance with the follow-ing regulations:

– BetrSichV “Operating Safety Directive”– TRBS “Technical Regulations for Operating Safety”– GefStoffV “Hazardous Goods Directive”– EN 60079 ff. ”Explosive atmospheres”

Outside of Germany, the relevant national regulationsmust be observed.

Without labelling, the permitted cooling temperature (roomtemperature at installation site) complying with EN 60034-1/ IEC 60034-1 is 40 °C maximum and -20 °C minimum and thepermitted installation height is up to 1000 m above sea level(different values are specified on the motor nameplate andcertified separately if necessary).

Risk assessment of possible discharges on stator windings – ignition risk factors

Characteristic Value Factor Rated voltage > 6.6 kV to 11 kV 4 > 3.3 kV to 6.6 kV 2 > 1 kV to 3.3 kV 0

Average start frequency > 1/ hour 3in operation > 1/ day 2 > 1/ week 1 < 1/ week 0Interval between detailed > 10 years 3inspections (see IEC 60079-17, > 5 to 10 years 2

Table 1, Type D) > 2 to 5 years 1

< 2 years 0 Type of protection (IP code) < IP 44a) 3 IP 44 and IP 54 2 IP 55 1 > IP 55 0Environmental conditions Very dirty and dampb) 4 Open-air coastal area 3 Other open-air areas 2 Clean open-air areas 1 Clean, dry interior 0

a) Only in clean environments and with regular upkeep by trained personnel, see 5b) “Very dirty and damp” includes areas exposed to flooding or includes open deck in the case of offshore applications.



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Care must be taken to ensure that the cooling air can flowunimpeded up to the air inlet holes and can flow freelythrough the air outlet holes without being immediatelydrawn back again. Suction and exhaust holes must beprotected from dirt and fairly coarse dust.

Figure 1.5: Minimum clearance at the air intake

The minimum distance between the fan cover’s air intakeand an obstacle (Bl measurement) must be observed at allcosts.

With designs which have the shaft pointing upwards, theoperator must prevent foreign bodies from falling verticallyinside. The same applies to the “shaft pointing downwards”installation – in this case, a protective cover is necessaryover the fan cover’s air intake grid. While installing thesurface-cooled motors, care must be taken to ensure thatthe condensate drain holes are at the lowest point.

In the case of closed condensate drain holes, the screwsmust be replaced using sealant, after the condensate hasbeen drained off. In the case of open condensate holes,it is necessary to avoid using water jets or pressurisedwater. There must be an absolute guarantee that the motorsare set up on a perfectly even base to avoid twisting duringthe tightening process. In the case of machines which are tobe connected, precise alignment must be ensured. Flexiblecouplings must be used if at all possible.

Connecting the motor Connection must be done by a specialist, complying with thecurrently applicable safety regulations. Outside of Germany,the relevant national regulations must be observed.

It is essential to observe specifications on nameplates.– Compare current type, mains voltage and frequency.– Pay attention to the circuit.– Pay attention to rated current for safety switch setting.– In the case of motors of the Increased safety “e”

type of ignition protection, you must pay attention to thetE time.

– Connect motor in accordance with the connection dia-gram supplied in the terminal box.

For earthing, there is an earth terminal on the housing orflange end shield, depending on the model and design ofeach motor. All the motors also have a protective conduc-tor terminal inside the terminal box. Unused cable glandsin the terminal box must be closed to protect them againstdust and humidity. The General Safety and CommissioningInstructions apply to the electrical connection. The cableglands or screw plugs must be certified for the Ex area.

The installation torques, sealing areas and clamping rangesspecified by the cable gland manufacturer must be observedat all costs.

Connection cables must be selected to comply withDIN VDE 0100, taking into account the rated current andmachine-specific regulations (e. g. ambient temperature,type of cable-laying etc., complying with DIN VDE 0298 orIEC/EN 60204-1).

At room temperatures of above 40 °C, cables with anapproved operating temperature of at least 90 °C must beused. This also applies to the motors in which reference ismade by an X to special requirements for cable design onthe supplementary sheet for EC type-examination certifi-cate.

In connecting the motors, particular care must be taken toset up the connections in the terminal box carefully. Theconnecting bolt nuts must be securely tightened withoutusing force. In the case of motors which have a terminalboard with slot terminal complying with Directive 94/9/EC,only cable lugs complying with DIN 46295 may be used forconnecting the motor. The cable lugs are fastened by nutswith integrated spring lock washers. As an alternative, a

solid wire is permissible with a diameter which correspondsto the width of the slot in the connecting terminal.

When inserting the leads in the terminal box, care must betaken to ensure that the wires are not under tension. Theinterior of the terminal boxes must be kept clean. The sealsmust be undamaged and correctly positioned. The terminalbox must always be locked during operation.

Safety measures against prohibited temperature risesIf no conflicting information regarding mode of operationand tolerances is provided in the test certificate or on thenameplate, electrical machines are designed for continuousduty (Mode of operation S1) and standard starting behav-iour without frequently restarting so that no significant tem-

perature rise is perceptible. The motors may only be usedfor the mode of operation specified on the nameplate.

Explosion-protected motors are generally designed andcertified for Range A of the voltage and frequency param-eters specified in EN 60034-1 (DIN VDE 0530, Part 1):

Voltage ± 5 %, frequency ± 2 %, characteristic curve, mainssymmetry. To an increasing extent, explosion-protected mo-tors are also being manufactured for greater supply voltagetolerances. This should be evident from the rating plate ofthe motor and, where appropriate, the EC type-examinationcertificate. There are thus numerous supplements to ECtype-examination certificate for a voltage tolerance of ± 10 %in accordance with Range B. It is imperative to observethe specified tolerances, so that the temperature rise

remains within the permissible limits. On start-up, it mustbe protected against prohibited temperature rises, e. g. withmotor protection switch, i. e. prohibited rises in temperaturein all phases must be prevented by a earth leakage circuitbreaker complying with DIN VDE 0660 or an equivalentdevice. The protection device must be adjusted to the ratedcurrent. Delta-connected windings must be protected byconnecting the tripping devices or relays in series to thewinding phases. Basis for the selection and adjustment ofthe switch is the rated value of the phase current, i. e. themotor rating current multiplied by 0.58. If such a connec-tion is not possible, suitable protection switches, e. g. withphase failure monitoring, must be used. For pole-changingmotors earth leakage circuit breakers must be equipped foreach speed that can be locked against each other.

The start is also monitored in the case of Increased safety“e” type of ignition protection. For this reason, the protectivedevice must switch off when the rotor is locked, within thetE time specified for the particular temperature category.

The requirement is fulfilled if the tripping time (found in the



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tripping characteristic curve (start temperature 20 °C for theI A /I

N factor) is no greater than the specified t

E time.

Electrical machines of the Increased safety “e“ type of igni-tion protection for starting with high inertia loads (ramp-uptime > 1.7 x t

E time) must be protected by a start monitor

in accordance with the specifications of the conformity certi-ficate and must also be certified accordingly.

Thermal machine protection by direct temperature monitor-ing of the winding is permissible, if it is certified and thet A time is specified on the nameplate. The explosion protec-

tion is guaranteed by temperature sensors complying withDIN 44081/44082, in conjunction with tripping devices with

II (2) G protection type identification.

Additional devices As an option, explosion-protected motors may be providedwith additional devices:

Additional thermal motor protection

For monitoring the stator winding temperature, temperaturesensors (PTC thermistors, KTY or PT100) may be installedin the motor. To connect them, suitable auxiliary terminalsfor auxiliary circuits are available either in the main termi-nal box or in additional terminal boxes. The connection ismade in accordance with the enclosed terminal connectiondiagram.

Thermal motor protection as full protection The use of the thermal winding protection as full motor pro-tection is only permissible if this mode is separately testedand certified by a notified body. In this case, identificationis completed on the nameplate by provision of the t

A -time

in place of the tE-time and the text “Operation only with

functionally-tested PTC tripping device with the protection

type identification II (2) G”. The I A /IN specification is notnecessary.

Anti-condensation heating The heating tapes must satisfy the requirements of Directive94/9/EC. The heat output and supply voltage are speci-fied on the motor nameplate. To connect them, suitableterminals for auxiliary circuits are available either in the mainterminal box or in additional terminal boxes. They are con-nected in accordance with the enclosed terminal connectiondiagram. The anti-condensation heating must be switchedon only after the motor has been switched off. It must not beswitched on during motor operation. This is guaranteed bylocking the circuit.

External ventilation unit The external fans must satisfy the requirements of Direc-tive 94/9/EC and must be suitable for the intended type ofignition protection.

The external ventilation unit is responsible for removing thedissipated heat when the main motor is operating. While themain motor is operating, the external ventilation motor mustbe switched on. After the main motor has been switchedoff, the external fan must continue to work until the tempe-rature is low enough. If there is a fault in the external fan, the

main motor must be switched off.

In the case of motors with external fan units dependent onthe direction of rotation, it is essential to pay attention tothe direction of rotation (direction-of-rotation arrow). Onlythe external fan units supplied by the manufacturer maybe used. The external ventilation unit must be connectedaccording to the applicable terminal connection table sup-plied.

External heat and cold sourcesIn the case of existing external heat and cold sources, noadditional measures are necessary if the permitted ambienttemperatures are not exceeded at the installation point.If they are, in fact, exceeded or effects on the operating

temperatures or maximum surface temperatures can beexpected, suitable measures for maintaining and certifyingthe explosion protection must be taken. If in doubt, consultthe manufacturer.

General instructions for operationon the frequency converter It is only permissible to operate explosion-protectedthree-phase motors in connection with frequency conver-ters, if the motors are built, tested, approved and labelledseparately for this mode. The separate manufacturer’sinstructions must be observed under all circumstances. Forthe Increased safety “e” type of ignition protection and formotors for use in Zone 21, separate EC type-examinationcertificates are necessary, in which operation in connec-

tion with frequency converters is explicitly approved and inwhich the binding conditions and parameter setting of themotor, frequency converter and protection device systemare listed. In the “n” type of ignition protection, motors ope-rated in connection with frequency converters at variablefrequency and/or voltage, must also be tested with thespecified frequency converter or a similar frequency converterin terms of the specification of output voltage and current.

The necessary parameters and conditions can be found onthe nameplate or the documentation of the motor.

In order to prevent prohibited temperatures, the motorsare equipped as standard with thermal winding protection,which has to be evaluated by a suitable device. The motorsmust not be operated as a group drive.

The manufacturer’s Notes and Operating Instructions forinstallation and commissioning of the frequency convertermust observed under all circumstances.




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2 Technologies for protecting induction machines from prohibited temperaturerises as a result of overload – Summary complying with explosion protection

2.1 What legal/normative specifications exist regarding protection ofelectrical machines in explosion hazard areas?

– Directive 94/9/EC: Directive 94/9/EC states the following regarding devices

in Category 2 (Equipment Group II), which include electri-cal machines operated in Zone 1: “Category 2 comprisesdevices which are designed in such a way that they canbe operated in accordance with the manufacturer-speci-fied parameters and guarantee a high degree of safety”.It is further stated as follows: “The machine-based ex-plosion protection measures in this category guaranteethe required degree of safety even in the case of frequentequipment faults or error situations which are normally tobe expected.” From this we can conclude that all equip-ment in Category 2 must not become an ignition source inthe case of errors and faults which are frequent or to be

expected. Furthermore, it is stated in article 1, paragraph 2:“Safety, control and regulation devices for use outside ofexplosion risk areas which, however, are essential for safeoperation of equipment and protection systems or contri-bute to them, are also included in the area of applicationof this directive.”The terms of the directive require that all motors inCategory 2 must be protected against prohibitedtemperature rises and that all equipment and devicesfor protecting the motor must be certified.

– ATEX guidelines: The ATEX guide specifies the Directive’s requirements of

the guideline and is itself produced by the Commission’sStanding Committee as a guideline. It is stated in chapter

3.10: “Safety, control and regulation devices are subjectto the directive, if they contribute to or are necessary forthe safe operation of equipment or protection systemsin terms of ignition dangers or the danger of an uncon-trolled explosion.” It is stated below: “These devices alsocome under it if they are to be used as intended outsideof explosion risk areas. These devices are not allocatedto categories complying with article 1.” It is also statedas follows: “The fundamental requirements apply to thesedevices only to the extent that they are necessary forthe safe, reliable mode of operation and handling of thisdevice, with regard to dangers of ignition or the danger ofan uncontrolled explosion.” The following explicit exampleis given: Overload protection devices for electrical motorsof the Increased safety “e” type of protection. There is no

statement regarding the protection of motors of the “d”,“p” and “n” types of ignition protection.The guide also states that motors of the Increasedsafety “e” type of ignition protection must be pro-tected definitively by a certified monitoring device inaccordance with Directive 94/9/EC.

– IEC/EN 60079-14 The operation of electrical equipment for explosion

protection is described by IEC/EN 60079-14. Applica-tion of the standard is not compulsory. In Chapter 7.1 astatement is made firstly on all electrical equipment: “Allelectrical equipment must be protected against harmfuleffects of short circuits and earth faults.” Further on, itsays: “Precautions must be taken to prevent the opera-tion of multi-phase electrical equipment (e. g. three-phasemotors) if the failure of one or more mains phases canresult in overheating.” There is also a statement on elec-trical machines at 7.2: “Rotating electrical machines mustalso be protected against overload, with the exception ofmotors which are continually capable of controlling thestart-up current in the case of rated voltage and rating

frequency or generators which are continually capable ofcontrolling the short-circuit current without a prohibitedtemperature rise. The following must be used as overloadprotection devices: a current-dependent, time-delayedsafety device for monitoring all three phases, not set anyhigher than to the machine’s rated current which, at asetting current multiplied by 1.2, must respond within2 h and at a setting current multiplied by 1.05 must notyet respond within 2 h or a device for direct temperaturemonitoring by embedded temperature sensors or anequivalent device.” The following statement is also made at11.3.1: “In order to satisfy the requirements of 7.2a),time-delayed overload protection devices must, dependingon current, be designed in such a way that not only is the

motor current monitored but also that the motor, with brakefully applied, is switched off within the tE time specified on

the nameplate. It is also stated regarding delta-connectedmachines: “For this reason, phase failure protection mustbe provided for machines with delta-connected windings,protection which recognises machine imbalances beforethey cause excessive temperature rises.”

In summon it is recommended that all electricalmachines in explosion hazard areas are protectedagainst overload, short-circuit and phase failure andthat the protection for the Increased safety “e” typeof ignition protection must be effective even when themotor is locked.

– IEC/EN 60079-7

The following statement is made on the tE time in chapter5.2.4.4.1 of the requirements of Increased safety “e” typeof ignition protection: “The t

E time must be long enough

for the current-dependent safety device to switch off thelocked machine within this period. This is usually possibleif the specified minimum values for t

E specified in Figure

2 (the standard), depending on the I A /I

N f initial starting

current relation, are exceeded. It follows from this that the area of the relation

between initial starting current and rated current isrestricted to the Increased safety “e” ignition safetytype and that the time t

E must conform to the mini-

mum values shown in Figure 2.4.

– EN 60079-1

In the standard for the Flameproof enclosure “d” type ofignition protection, there is no statement on protection ofrotating electrical machines. For calculating the maximumsurface temperature, the test voltage of U

A ± 10 %

is prescribed (or U A ± 5 %, if the area of application is

specified on the equipment and is named in the operatinginstructions). No requirements are made of the overloador fault conditions.

– EN 60079-2 The standard governing Pressurized enclosure does not

contain any statement on protection of rotating electricalmachines.

– EN 60079-15 In contrast to the above-mentioned types of ignition pro-

tection, the equipment for type of ignition protection “n”comes into Category 3 of Directive 94/9/EC. Equipmentin this category must not have any ignition sources duringnormal operation. The following statement on the electri-cal machines standard appears in Section 17.8.1: “Thetemperature of each exterior or interior surface which may



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come into contact with an explosive atmosphere mustnot exceed the temperature category specified in Section5, in normal operating conditions. The temperature riseduring the start does not have to be considered for spe-cifying the temperature category when S1 or S2 is givenas mode of operation complying with IEC 60034-1. It is

further stated as follows: “Not taking the start conditionsinto account in specifying the temperature category ispermissible for machines which do not start frequently

and with which the statistical possibility of an explosiveatmosphere existing during the start-up process is notconsidered to be highly feasible.“

The machine has to maintain the specified tempe-rature category in normal operation only. The start

does not have to be monitored. There is no directstatement on errors occurring.


2.2 Causes of prohibited high temperatures in an electrical machine

The most frequent cause of prohibited high temperaturesin an electrical machine is overloading, i.e. loading at ahigher torque than the machine’s rating torque. Reasons forthis may be as follows: faulty design of the drive, sluggishworking machine, damage after long-term storage, vis-cosity of medium too high in stirring devices etc. With anincreased load, the currents in the stator winding and rotor

squirrel cage increase, with the copper losses increasingquadratically with the current. Another cause of a prohibi-ted temperature rise in the machine is operation outside ofthe machine’s rating parameters. Examples of this are asfollows:

– Undervoltage operation: With operation at decreasedvoltage, the machine’s stator currents increase, in orderto deliver its required output including motor losses.

Because of the decreased voltage for the main in-ductance in the machine’s equivalent circuit diagram, a

reduced magnetic flow density is produced in the air gap,which results in an increase in the machine slip rate evenwith constant load torque. Concerning the P

VCu2= s . Pd

gives the relationship that explains the effect of significantincrease in copper losses in the machine’s rotor. Ultima-tely the machine is “tilting”, whereby the speed dropssteeply and the stator current increases to that of the

initial starting current.

– Overvoltage operation: If the voltage is increased abovethe rated voltage range, a magnetic oversaturation of themachine occurs. As soon as the operating point in thesheet’s B-H characteristic curve moves into the linearrange and the value of µ

r approaches 1, very high magne-

tisation currents flow and the core and stator windinglosses increase sharply. The result may be a prohibitedtemperature rise in the machine. Figure 2.1 illustrates thesituation.

Figure 2.1: Voltage-dependent no-load loss curve

– Voltage imbalances/phase failure: Overvoltage im-balance and, in the extreme case, the failure of a phasedo not necessarily cause the motor to stop. In the caseof a low mechanical load, it results only in an increase inthe slip rate. That is why there is a risk that this fault willremain undetected for a fairly long period. However, themotor no longer starts with only two remaining phasesand corresponding load moment.

If the motor is star-connected, an increase in current mustbe recorded in the remaining phases. If the current ex-

ceeds the machine’s rated current, prohibited temperaturerises may occur. The motor protection switch must detectthe overcurrent and switch the motor off.

With a delta-connected motor, a phase failure (in accord-ance with Figure 2.2) results in the winding phase carryingto cease to carry the <1 / 3-times conductor current butthe 2 / 3-times conductor current instead of. A thermaloverload of the winding phase is therefore possiblewithout the protective device registering an overcurrent.It follows, however, from EN 60079-0 that the protective

0

200

400

600

800

1000

1200

1400

1600

1800

2000

0 100 200 300 400 500 600 700

UN

Voltage/V

P o w e r l o s s / W

Total no-load losses

Iron + friction losses

Stator winding losses



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device must detect machine imbalances before prohibi-ted temperature rises occur. This fault must, therefore,be detected by a certified motor protection device. Thecause of the phase failure may be a tripped fuse or else aclamped connection which has worked loose.

The interruption of a winding phase inside the motor,in the case of a delta connection, is to be regarded asespecially critical. In this case, the uninterrupted windingphases are charged with the full conductor current. In or-der to accurately detect this fault, also, the motor protec-tion switch must be switched on directly to the windingphases and be set to the 1 / 3-times motor rated current,in order to regulate out ignitable temperature rises andthermal damage to the winding.

– Inadequate cooling: If the cooling air routes are blockedor the motor is operated at an excessive ambient tempe-rature, there is a danger of prohibited temperatures, evenwithout any overload. This fault can be detected only bydirect temperature monitoring.

– Converter mode: Frequency-converter operated ma-chines, as long as they are self-ventilated, are driven by aheat dissipation system, with speed varying according tothe environment. At every point in time, the balance fromthe fundamental component losses including the harmo-nic losses as well as the heat dissipation to the environ-ment and the machine’s heat-accumulation capability aresafeguarded, in order to prevent a prohibited temperaturerise.

– Voltage drop at start: If voltage drops should occur inthe case of high network impedances during the start-upprocess, this results in an approximate linear reduction ofthe initial starting current by the voltage and in a quadratic

reduction of the breakaway torque.

Figure 2.2: Delta connection in the case of phase failure

Thus there is a risk that the machine will not start at theappropriate load moment. At the lower starting currentaccording to figure 2.4, an extension of the motor protec-tion switch’s switch-off time also results when the machinedoes not start. It is essential to ensure that the machineis not subjected to any prohibited temperatures within the

extended switch-off time.

IS1

IS3

IS2

U

V W

IL3

IL2

IL1

L1 L2 L3

Undisrupted operation:

IL1

= IL2

= IL3

= 3 . IS

Phase failure L3:

IL1

= IL2

IS1

= 2 . IL1

3

IL3

= 0 IS2

= IS3

=1 . I

L1

3

2.3 Protection principles for mains-operated machines andrequirements of protection with explosion-protected drives

2.3.1 Type of ignition protection – Flameproof enclosure “d”

With this type of ignition protection, the principle is basedon the fact that an explosion may occur in the interior ofthe motor and is allowed to do so but that the latter isnot transferred to the surrounding explosive atmosphere

because of the housing design. From an explosion pro-tection point of view, the only thing that, therefore, mustbe required of these motors is that the exterior surfacesdo not heat up beyond the certified temperature catego-ry in normal operation and in the case of faults, and thatthe seals, connection cable and other attachments arenot thermally overloaded. These motors may be thermal-ly protected by a time-based over-current trip and also

by PTC thermistors embedded in the winding. It can betaken from Directive 94/9/EC and Standard EN 60079-14that motor protection is absolutely necessary. Locking,however, is not considered separately – something which

also does not necessarily have to be essential because ofthe housing’s high heat capacities. In the case of locking,even if rotor and stator windings are supposed to haveheated up above the ignition temperature when the motorprotection responded, the housing will only reach distinctlyreduced temperatures because of the distribution of theheat energy to a higher thermal capacity.



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2.3.5 Type of ignition protection – Dust explosion protection “t”

For dust-explosion-protected machines in accordance withthe standard EN 60079-31, a further core requirement –alongside the aforementioned verification of the enclosureprotection – is observance of the maximum surface tem-perature specified in the EC type-examination certificate.

The surface temperature is determined by way of electrical-

thermal testing for rated-duty operation, for operation at the

upper and lower limits of the rated voltage range and afteroverload testing with 120 % rated current for two hours,starting from a state of thermal equilibrium after rated-dutyoperation. This is intended to simulate disconnection via themotor circuit-breaker in case of overload. For all tests, it isimportant to take into account the subsequent further warm-

ing of the housing after the end of the actual test duration.


2.3.2 Type of ignition protection – Pressurized enclosure “p”

This type of ignition protection may be considered in thesame way as the Flameproof enclosure. In this case also,only the external surface temperature is relevant to explo-sion protection. No combustible mixture can penetrate the

motor’s interior, as an explosion protection gas, for example,

is maintained under overpressure here. As an additionalcondition, there must be a guarantee that internal parts arecooled down to values below the ignition temperature of thediffusing mixture when the mixture reaches them, if the igni-

tion protection gas supply fails and the motor switches off.

2.3.3 Type of ignition protection – Increased safety “e”With this type of ignition protection, the ignitable mixture isallowed to penetrate the motor’s interior but must not comeinto contact with any ignition sources. For that reason,special requirements are set of the motor protection inaccordance with EN 60079-14, in order not to reach any

prohibited stator or rotor temperatures at rated voltage,even in the case of locking. The direct temperature monitor-ing or a time-dependent overcurrent trip may be used asprotection principles.

2.3.4 Type of ignition protection – “n”

For this type of ignition protection, the machine only has

to maintain the temperature category in “normal operatingconditions”, in accordance with EN 60079-15. It is statedexplicitly in the standard that the case of locking does nothave to be considered for operating modes S1 and S2.Overloading is not mentioned. In the case of operating

conditions which cannot exclude overloading without pro-

tection and could remain undetected for a long time, theycontradict the theory of this type of ignition protection. Atype of overload protection similar to the Increased safety“e” type of ignition protection is adequate.

2.3.6 Direct temperature monitoringIn the case of direct temperature monitoring as sole protec-tion, PTC thermistors are embedded in all three of the wind-ing head’s three winding phases and impregnated alongwith the winding. This guarantees a strong thermal contactbetween winding and PTC thermistor, which is extremelyimportant for the effectiveness of the protection principle.

The individual PTC thermistors are connected in series andlinked to a PTC thermistor tripping device, usually fittedoutside the explosion hazard area, during motor installa-

tion. If the PTC thermistors are heated up past the nominalresponse temperature e. g. 130 °C, the resistance increasessteeply and is registered by the evaluation unit. When thenominal switch-off temperature is reached, the motor isswitched off. The unit must also detect resistance whichis too low and beneath the PTC thermistor’s “window ofresistance”. The reason for this may be a short circuit in thePTC thermistor’s connecting wiring, which stops protectionfrom being guaranteed. Protection by direct temperaturemonitor restricts the winding temperature to a fixed value.

By this means, it is possible to also detect prohibited tem-peratures which are attributable not to an overload but, forexample, to blocked cooling air routes or to an excessiveambient temperature. From the point of view of pure currentmonitoring, this is a safety benefit.

In the design of the PTC thermistor for sole protection, caremust, however, be taken to ensure that the rotor as well asthe stator must be protected from prohibited temperatures

(Increased safety “e” type of ignition protection and type ofignition protection “n”). This is a challenge for rotor-criticalmachines in particular and many machine designs do notpermit sole protection via PTC thermistor.

In the case of a machine with sole thermal protection viaPTC thermistor being tested, these cases must be consi-dered and the “protection’s equal quality to current monitor-ing” proved by calculation and experiment.

2.3.7 Current-dependent, time-delayed safety equipment

Motor protection via current monitoring is based on the ap-proach of the motor protection relay representing a simplifiedthermal image of the motor and shutdown occurring in thecase of a prohibited temperature rise registered by this ther-mal model. In addition, the motor protection switches containanother magnetic instantaneous trip for short-circuit pro-tection. The simplest design of motor protection device is amotor protection switch with thermorelay. Here the bimetal is

heated up by a heating winding with the motor current flow-ing through it. The bimetal may be regarded as a single-bodyequivalent motor circuit. Bimetals of this type exist for all threephases and different temperature rises in the bimetals andthus also a single phase overload and current imbalances aredetected, by means of a mechanical link. In accordance withEN 60079-0, the protective device must not trip within 2 h,even when the rated current of the motor is 1.05. However



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in the case of current multiplied by 1.2 it must respond within2 h. The following consideration clarifies the motor’s thermalbehaviour:

For the single-body equivalent circuit, it is possible to write

P V = + c .

P V is the converted power loss in the machine, J the

overtemperature for the environment, Rth the heat transfer

resistance for the environment and c the machine’s heatcapacity. The following may thus be written for the tem-perature:

J= . (1- e - )

It follows from this equation that the rise in temperature,e. g. after the overloading has occurred in accordance withan e-function, approximates the new “steady state tem-

perature” .

J

Rth

∆J

dt

P V

R th

tR . c

4

5 6 7 8 9 10

I A / I

N

EN 60079-7

VIK

For this reason, there must be a shutdown to safely protectthe motor, before the overtemperature J in the stator orrotor reaches prohibited values.

The motor’s load-dependent losses may be seen as an initialapproximation in quadratic dependency on the machine cur-

rent, with the result that the integral must be evaluated by∆J ~ I2 tdt

in the case of overload. In the most basic case, the evalua-tion may occur via the previously mentioned bimetal. Elec-tronic protective devices, however, which guarantee a moreprecise response, respond with a freely-definable currentimbalance factor, and are able to represent the machinebetter thermally by means of a more expensive thermalmulti-body equivalent circuit, and are becoming increasinglywidely distributed, particularly in the case of larger drives.

As an alternative, there is also the possibility of monitoringthe motor’s active power input by an electronic protectivedevice. This may be advisable with machines which have

a very low current input in the case of overload or if, in thecase of pump drives, for example, a drop in power mustalso be recognised as dry run prevention.

P V

R th

2.3.8 Protection selection and parameterisationwith type of ignition protection – Increased safety “e”

In Figure 2.3 we see the worst fault in thermal terms for amachine, the motor locking at operating temperature. The

Figure 2.4: Tripping characteristic curve for current-dependent motor protection devices complying withEN 60079-7

motor protection must switch off the motor within its tE heat-

ing period stated on the EC type-examination certificate.

Figure 2.3: Definition of tE time

In order to be able to guarantee that it is switched off atthe right time, the motor protection device must firstly becorrectly set to the motor’s rated current. The other conditionis that the t

E time calculated by measurement in the case of

the motor’s measured initial starting current relation shouldalways be higher than the tripping characteristic curve formotor protection relay contained in Standard EN 60079-7,5.2.4.4.1 (Figure 2.4). The permissible initial starting current/ rated current relation is within the range of 3-10 for machinesof the Increased safety “e” type of ignition protection (for VIKmotors, this range is limited). In addition to the shutdown ofthe machine in the cases of “Overload” and “Locking”, thefollowing more detailed requirements are made of the motorprotection device, in order to guarantee safe operation of themotor:

– Protection against accidental adjustment– No automatic restart after tripping– Start monitor– Short-circuit detection– Detection of prohibited current imbalances– Test possibilities– Detection of safety-specific interior faults and transfer

to safe state (shutdown)– Minimum required: SIL Category 1– Shutdown within 2 h in the case of overload at 1.2 times

motor rated current– “Thermal Memory” in the case of supply voltage

interruptions

Hours Seconds

tE time

Prohibited temperature range

Permitted temperature range in the event of a fault

Continuous duty temperature range

1 1.5 2 34

5

10

20

40

60

120

tE / s



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2.3.9 Current and temperature monitoring

For special instances of use, it is advisable to protect themotor by a direct temperature monitor in addition to thecurrent monitor. Such a case occurs if, for example, opera-tion results in having to deal with excessive ambient tempera-

tures or blocking of the cooling air routes at the motor’s

installation site. In the case of this “hybrid protection”(Figure 2.5) the PTC thermistor does not have to bedesigned for sole protection, as overload and locking aredetected by the current monitor.

Figure 2.5: Motor protection by current andtemperature monitoring

2.4 The motor in combination with other equipment

If the motor is directly connected to the machine, whichhappens very frequently in practice, it is no longer sufficient

to consider the motor as detached from the environment,from a thermal point of view. This is particularly the case ifthe machine reaches a higher temperature than the motorand heat flows materialise towards the motor.

In the case of a pump, this can occur when hot substancesare being pumped. Figure 2.6 illustrates the situation.

When considering the combination of motor and pump, notonly the temperature category of any gases has to be taken

into account, but also the limit temperatures of the motor’scomponents and attachments. In this case, the bearing inparticular should receive the necessary attention, if heatflow caused by the shaft is expected. Excessive bearingtemperatures may result in a premature failure of the bearingpossibly combined with combustible conditions.

Figure 2.6: Motor-pump assembly

Explosion risk area

Monitoring devices as perDirective 94/9/EC for equipment inexplosion risk areas

Motor protection switch

Motor

Power supply

Motor Pump

Medium

Flange Flange

ShaftShaft

Environment

Base Base/pipes

PTC thermistor tripping device



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The motor with gearbox connected is another very commoncombination. In this case also, the gearbox temperature risemust be taken into account in the selection and design ofthe drive. This does not apply if motor and gearbox havebeen obtained from the manufacturer as one unit.

In accordance with Figure 2.7 the gearbox is frequentlydesigned as a combination of “Structural Safety” and “Fluidencapsulation” types of ignition protection.

Figure 2.7: Combination of the “c” and “k” types of ignitionprotection with a gearbox (“c“ and “k”…mechanical explosion protection)

Directive 94/9/EC details the following possibilities for as-sembling two devices (e. g. motor and pump):

1. Motor and pump cannot be assessed separately: thecombination is subjected to the conformity evaluationprocess for electrical equipment.

2. Motor and pump may be assessed separately: If no otherignition dangers occur, the unit does not come under thedirective’s area of application; a unit is produced whichconsists of two individual devices which each have aseparate declaration of conformity.

3. The assembly’s manufacturer wishes to submit a com-prehensive declaration of conformity: obligation to carryout an ignition risk evaluation; creation of documentation;CE label and declaration of conformity; manufacturerbears full responsibility; third-party certification notnecessary

4. Additional ignition hazards resulting from a combina-tion or a component is not in full compliance with thedirective: The combination must be subjected to thecomplete conformity evaluation process.

In addition to the thermal influences already described, allother values affecting explosion protection must be takeninto account. Here the devil is often in the detail. Thus, forexample, the topic of “Electrostatics” must be subjected toconsideration besides the effects on motor cooling whenattaching a plastic noise protection cover.

2.4.1 Recommended maximum interface temperatures for flange motors

As a result of connection to machines, temperatures above40 °C may occur in flange motors, both on the flange andon the shaft end. It is required of motors of Ex d and Ex e

type of ignition protections in accordance with VE 1/NE 47that they still adhere to the conditions of explosion protec-tion, as long as the interface temperatures specified beloware not exceeded.

Note 1: The specified limit values are published in agreementbetween VDMA and ZVEI as a VDMA standardsheet for pumps built as a block assembly.

Note 2: With the exception of the specified interface tem-perature, no other real heat input to the machine’sactive parts from shaft end and flange is expected.

2.4.1.1 Machines of type of ignition protection – Flameproof enclosure “d”in mains operation

Temperature category T3 T4 T5 T6Max. shaft temperature 100 °C 100 °C 85 °C 70 °CMax. flange temperature 100 °C 100 °C 85 °C 70 °C

General conditions:– Maximum permissible temperatures on shaft end

and motor flange– No converter mode

2.4.1.2 Machines of type of ignition protection – Flameproof enclosure “d”in converter mode

Temperature category T3 T4 T5 T6Max. shaft temperature 100 °C 100 °C - *) - *)

Max. flange temperature 100 °C 100 °C - *) - *)

*)

Still under discussionGeneral conditions:– Maximum permissible temperatures on shaft end

and motor flange– Adjustment range from 10 Hz to f

N ( <

= 60 Hz)– Self-ventilated

– Self-ventilated– Size from 63 to 200,

motors in accordance with EN 50347– Applies to ambient temperatures from -20 °C to +40 °C– 2 and 4 pole motors

– Size from 63 to 200, motors in accordancewith EN 50347

– Applies to ambient temperatures from -20 °C to +40 °C– 2 and 4 pole motors– Individual test necessary



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2.4.1.3 Machines of type of ignition protection – Increased safety “e”,temperature category T3

Pole number 2-pole 4-poleMax. shaft temperature 60 °C 75 °C

Max. flange temperature 60 °C 75 °C

General conditions:– Maximum permissible temperatures on shaft end and

motor flange– No converter mode– Self-ventilated

– Size from 63 to 200– Motors in accordance with EN 50347

and DIN V 42673-2 (formerly DIN 42677-2)– Applies to ambient temperatures from -20 °C to +40 °C

3 Frequency-converter operated explosion-protected drivesand safety measures

In the case of Flameproof enclosure “d” and Pressurized

enclosure “p”, the explosion protection principle is basedon the fact that either an explosion occurring in the housinginterior is not transferred to the surrounding atmosphere(Flameproof enclosure “d” type of ignition protection) or elsethe explosive atmosphere cannot penetrate the housinginterior during operation (Pressurized enclosure “p” type ofignition protection). With these types of ignition protection,the temperature of the exterior surfaces, which must notexceed the temperature category’s limit temperature, is thedecisive criterion. In the case of the Pressurized enclosure“p” type of ignition protection, there is the addition of thelimiting condition for the maximum temperatures in thehousing interior that the residual heat stored cannot ignitediffusing gas if there is a failure of the ignition protectiongas supply and the motor is switched off. In the case of the

Flameproof enclosure “d” type of ignition protection, sui-tability for operation on the frequency converter is certifiedacross-the-board in the EC type-examination certificateby the notified body. The same applies to the Pressurizedenclosure “p” type of ignition protection.

The interior temperatures are otherwise not relevant toexplosion protection. There must, however, be a guarantee

in terms of operating safety and availability that the per-

mitted operating temperatures of the insulation materialsand other installed components are not exceeded. Thesemotors are protected by PTC thermistors in a similar way tothe mains-operated motor, with evaluation unit embeddedin the winding. Slot resistance thermometers may be usedas an alternative.

With the Increased safety “e” type of ignition protection, theequipment’s explosion protection is based on the preventionof an explosive atmosphere igniting, whereby the explosiveatmosphere can also penetrate the equipment’s interior.With an asynchronous motor, the possible ignition sourcesare hot surfaces, mechanically-produced abrasion and im-pact sparks and electrical discharges. In order to eliminatethem, increased requirements of the mechanical structure

and design of the electrical insulation system, as well asprotection from prohibited high temperatures, are necessaryin the case of explosion-protected motors. With frequencyconverter operated machines, there are additional dangersof ignition due to “Electrical Discharges” and “Hot Surfaces”ignition sources compared with mains operation, ignitiondangers which must be taken into consideration for themachine’s design and for certification.

3.1 Electrical discharges

Caused by the power transistors’ fast switching operationsand thus high voltage increase speeds, travelling wave

processes form on the motor wiring, whereby the motor’sand converter input’s impedances, effective for the high-fre-quency processes, differ from the wiring’s wave impedance.Z

motor >> Z

wiring generally applies, so that a reflection factor of

approximately 1 is produced for the voltage wave running inthe direction of the motor and the wave is reflected. In thecase of electrically long wires compared to the frequencyof these travelling wave processes, transient voltage peaksoccur as far as the double intermediate circuit voltage onthe motor terminals (Figure 3.1). The clearances in themachine’s terminal box would have to be sized to thetransient overvoltages, whereas the creepage distances inaccordance with EN 60079-7 must be designed only for theconverter output voltage’s RMS value. In accordance withEN 60079-7, short-term voltage peaks do not result in theformation of erosions caused by leakage currents on thesurface.

With low voltage machines, it has proved effective in prac-tice to design the terminal box’s rated voltage according

to the frequency converter input voltage, as long as notransient overvoltages occur at an amplitude higher thanthe double intermediate circuit voltage. If multiple reflectionsand thus higher voltages are to be expected, the next high-est rated voltage step must be chosen for the terminal box.

This procedure is recommended by the PTB.

It is also very important, however, for the winding insulationto be designed for these high, steep-flank voltage pulses.

The winding insulation in the winding input zone is alsoseverely stressed, as a major proportion of the voltage iscleared here. If partial discharges occur here, that results indestruction of the organic enamelled wire insulation over sus-tained periods and finally in an ignitable flashover and failureof the motor. If the motor manufacturer cannot guaranteeabsence of partial discharge, a filter must be connectedupstream, in order to reduce the winding’s voltage stress.



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Figure 3.1: Development of transient overvoltages on a frequency-converter operated drive

3.2 Hot surfaces

If an electrical machine takes on a prohibited temperature,the reasons are either an excessive heat loss inside themachine, for example, as a result of overload, or insufficientcooling. Reason for a prohibited overload, especially in themachine’s rotor, may also be operation beyond the motor’sspecifications, for example, at undervoltage.

These effects must be overcome by technical protectiondevices and operating parameter limits specified in the ECtype-examination certificate and dangers of ignition must beeliminated. In addition to the the limitation imposed by thetemperature category, the continuous duty temperatures of

the winding insulation, seals and other attachments mustnot be exceeded, in order to prevent premature ageing,along with possible ignitable failure. With the indirect voltage

link converter normally used today, additional temperaturerises in the motor caused by the harmonics are very rare,even without sine wave output filter, and are less than 10 Kin most cases in the PTB-inspected motors complying withthe permitted operating parameter limits. In the design ofthe converter in accordance with the specifications of theEC type-examination certificate for the motor, the “lockedmotor” fault does not have to be considered. For thatreason, the temperature reserve maintained for it may bedistinctly reduced. On the other hand, a very importantpoint is the increase in the thermal resistance to the environ-ment with a reduction in speed in the case of self-ventilated

machines. In Figure 3.2, this relation is applied to twomachines of sizes 180 and 132.

Figure 3.2: Characteristics of thermal resistanceto the environment dependingon speed

Non-explosion-hazard zone Explosion-hazard zone

Single-phase equivalent circuit

Wiring1556 V

I1

I’2

R1 X 1 X’2

U1

X h

R’2s

Zmotor

ZWiring

Motor

Offset frequency

300 kHz…3 MHz(Clearance and

creepage distances,winding)

Pulse frequency

1 kHz…20 kHz(Bearing, additional

temperature rise[skin effect])

Converter

Basic frequency

5 Hz…50 Hz…87 Hz(Temperature rise)

25…500 m

PTC thermistortripping device

778 V 500 V eff

+ 10 %

Mains supply

0 200 400 600 800 1000 400 6001200 1400 1600 1800 2000 2200 2400 2600 2800 30000.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

R t h

/ K / W

n / min-1

Measurement points BG 180

Polynomial regression (BG 180)

Test measurement BG 180Measurement points BG 132Polynomial regression (BG 132)

Test measurement BG 132



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This effect is considered in the new testing and certifica-tion concept for frequency converter operated drives, ofthe Increased safety “e” type of ignition protection, by avariable speed current limit in the frequency converter.In Figure 3.3, the maximum machine current related tothe rated current of a machine of size 132 is shown as

an example. All the operating points below the curve arepermanently permissible but those above the line are onlypermissible for a limited time, which is calculated in de-pendence on the overload. With a machine current greaterthan the 1.5-times rated current, an immediate shutdownoccurs.

Figure 3.3: Variable speed current limitation,from the EC type-examinationcertificate

The nodes in the curves have been detected by measure-ments in the PTB. In addition to this protection by means offrequency-dependent current monitor, a second protectivedevice is required, certified as a monitoring device in accord-ance with Directive 94/9/EC, as the frequency converter isnot certified and that is also not desired by the manufactu-rers. This protective device amounts in most cases to directtemperature monitoring via triple PTC thermistor with testedPTC thermistor evaluation device. The direct temperature

monitoring has a further advantage in that other faults, suchas a blocked fan grid or excessive ambient temperatures,are detected.

Also very important for safe operation is compliance withthe motor’s operating parameters specified in the data

sheet, whereby the fundamental oscillating voltage onthe motor terminals is given particular significance. If, forexample, the voltage drop on the converter and the motorconnection cables is not adequately taken into account, themotor slip increases in the case of unmodified torque andthe rotor, in particular, heats up very intensively. The voltagedrop must also be taken into account in any case if a sineoutput filter to reduce overvoltages is connected betweenmotor and frequency converter.

Figure 3.4 illustrates the situation. The motor has to beauthorised for the expected motor terminal voltage or theedge frequency adapted accordingly.

Figure 3.4: Voltage drops between mains and motor

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

f / Hz

Star connection Delta connection

0.5

0.6

0.7

0.8

0.9

1

1.1

I / I n

Permitted area

Prohibited area

Medium voltage Low voltage

Mains Transformer Frequency converter Sine filter Wiring Motor

400 V 390 V 375 V 370 V

Site

F u n d

a m e n t a l o s c i l l a t i n g v o l t a g e / V



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3.3 Harmonic losses

A further source of losses and thus of temperature riseswith a frequency converter operated drive are the harmoniclosses caused by the frequency converter input. This iscaused by the voltage harmonics contained in the motor’s

supply voltage which contribute nothing to the motor’storque but, however, result in current flowing through themotor and thus in losses both in the iron (eddy losses) andin the stator winding and the rotor cage (ohmic losses). Gra-phically presented, the machine may be subdivided into the“fundamental mode motor” formed by the torque and multi-

ple “Harmonic motors” arranged on the shaft, whereby thesuperposition principle is applicable because of the differentfrequencies. It can be seen very clearly from this graphicpresentation that the harmonics losses increase both with

the number of harmonic occurring and with their amplitude.Here it becomes clear that the frequency converter inputvoltage or the difference between the RMS value and themotor voltage’s fundamental oscillation value have a directeffect on the harmonic losses, as shown by the measure-ment in Figure 3.5.

Figure 3.5: How the harmonic losses depend on theconverter input voltage

To limit the harmonic losses it is, therefore, necessary tolimit the converter’s supply voltage. This value is thus also

listed in the EC type-examination certificate. If thesespecifications are observed, the harmonic losses are slightcompared with the fundamental mode losses (below 10 %)and do not result in prohibited temperature rises.

3.4 Increase in energy efficiency

This new approach will also contribute to an increase inthe proportion of frequency converter operator drives inthe chemical industry, as a result of which extremely high

energy-saving potential is produced, particularly in the caseof the drive for fluid flow machines. The result of a compa-rison of the energy efficiency of the flow rate adjustmentby bypass or reducing valve and the pump’s direct speedadjustment by means of frequency converter is shown

in Figure 3.6. The general conditions adopted were thepump’s rated output of 50 m3 /h at a pressure of 7 bar. Aflow rate of 30 m3 /h required by the process was applied for

the consideration in Figure 3.6. At assumed 5,000 part loadannual operating hours and a motor rated output of 18 kW,the amortisation period for the frequency converter is oftenless than one year, at today’s energy prices.

0

200

400

600

800

1000

1200

1400

1600

1800

490 540 590 640 6900

50

100

150

200

250

U e f f – U

h 0 1

/ V D i f f e r e n c e

H a r m o n i c l o s s e s

/ W

Converter input voltage/V

Harmonic losses BG250M4 deltaHarmonic losses BG250M4 starHarmonic losses BG200L4 deltaHarmonic losses BG200L4 star

Ueff

-Uh01

deltaU

eff -U

h01star

1.5 kW 3.9 kW 3.8 kW

Electrical

power

Hydraulic

powerMains Motor Pump Valve

100 % 90 %70 %

60 %

15 kW

5.7 kW

Operation on mains



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Figure 3.6: From electrical to hydraulic power

All in all, the energy-saving compared to the flow rateadjustment by means of valves with increasing pumpthrottling, i. e. reduced flow rate, increases. If the pump isoperated in the unthrottled state, the other hand, insignifi-cantly higher losses compared to direct mains operation areproduced because of the converter’s losses and the motor’s

harmonic losses.

If, because of the process, the pump is constantly driven atits rated flow rate, retrofitting of a frequency converter is notadvisable.

Figure 3.7 shows the estimated amortisation period for afrequency converter (purchase price 2000 euros) depending

on the flow rate (motor output 18 kW and kWh price0.19 euro).

In actual use, it is highly improbable that the pump is con-stantly operated at the same hydraulic capacity over theperiod. It is much closer to practice to adopt various loadprofiles for an estimation of the energy-saving potential, witheach expressing the dividing-up of various capacities overthe total operating period of one year.

For the assessments carried out in this case, the three loadprofiles shown in Figure 3.8 were adopted. In that case apump period of use of 5000 hours in total within one yearwas assumed. The bars show the time proportion of thehydraulic capacities (50, 30, 10, 5 m3 /h) with the rated flowrate amounting to 50 m3 /h.

Figure 3.7: Frequency converter amortisationperiod (purchase price2000 euros), depending onrelation of flow rateto rated flow rate.

Figure 3.8: Classification of the hydrauliccapacity by time

0.38 kW 0.99 kW 2.3 kW

Electrical

power

Hydraulic

power

Mains Converter Motor Pump

100 % 96 %89 % 70 %

9.4 kW

5.7 kW

Operation on converter

0 10 20 30 40 50 60 70 80 90 100

Flow rate/%

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

O p e r a t i n g h o u r s / h

Amortisation

50 30 10 50

10

20

30

40

50

60

70

60 60

50

25

15 1512

2225

3 3

10

Load profile 1

Load profile 3

Load profile 2

Flow rate m³/h

%



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If the costs occurring over the period for the mains opera-tion and for the operation on the frequency converter arecalculated adopting the load profiles shown in Figure 3.8,then because of the simplified adoption of constant motor

output for mains operation (flow rate adjustment by a by-pass valve), a straight line is produced running through thecoordinate origin, with the energy costs per time unit as theincline (mains operation costs).

Figure 3.9: Energy cost characteristics over

the period for mains operationand for frequency converter operation. Frequency converter purchase

cost: 2000 euros

The costs in the amount of 2000 euros for the converter-ope-rated drives, already generated at t = 0 time, correspond tothe accepted purchase costs of the frequency converter. Asindicated by the dotted lines, the amortisation period in daysis produced from the points of intersection of the straightlines for converter operation and mains operation.By means of the relation shown in Figure 3.9, the amortisa-tion periods for any investment costs (parallel move of the“converter curves”) and for other, possibly more favourable

methods (in terms of energy) for conventional flow rate adjustment (flattening of the “mains curve”) may be determined.

But even with a considerable extension of the amortisationperiods, the use of frequency converters for driving fluid flowmachines is associated in most cases with major financialsavings and other advantages, for example, optimisation ofprocess management and prevention of voltage drops onstarting high-output pumps.

3.5 Summary and outlook

A motor protection device for converter operated drives iscurrently being developed in collaboration with a certaincompany. When the device is in use, frequency conver-ters without variable speed current limitation can also beused and the PTC thermistor is also no longer necessarilyrequired. Figure 3.10 shows the protective device’s possibleuse.

Figure 3.10: Monitoring the motor in converter mode

0 30 60 90 120 150 180 210 240 270 300 330 360 3900

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

11000

12000

1300014000

15000

156 215 260

Days

E u r o

Mains operation costsSupplied converter cost profile 1Supplied converter cost profile 2Converter operation cost profile 3

Laptop

ParameterisationShutdown in the event of an error

Current measurement

Current converter

Motor

Optional:Direct temperature monitoring

Converter Voltage frequencymeasurement

Directive

Experience to date with the new testing and certificationconcept for frequency-converter operated drives of theIncreased safety “e” type of ignition protection is extremelypromising and it is apparent that certification for operationon the converter up to Temperature Category T3 is easilypossible. A requirement of safe operation, however, is thatthe motor’s operating parameters specified in the datasheet are observed and the winding is suitable for the vol-tage pulses which occur.



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3.6 Operation on frequency converter with use inZone 2 (Ex II 3G) or Zone 22 (Ex II 3D)

Operation on the frequency converter is only possiblewithin the operating points specified on the nameplate. Itis permitted to exceed the machine rated current up to 1.5times the rated current for a maximum of 1 min with a timeinterval of 10 min. By no means can the specified maximumspeed or frequency be exceeded. By selecting a suitableconverter and/or using filters, it can be guaranteed that themaximum permitted pulse voltage on the motor terminals isnot exceeded.

It is necessary to ensure that the operating voltage at themotor terminals complies with the specifications on thenameplate (watch out for voltage drop because of filter!).

Thermal winding protection must be assessed either by aseparate tripping device or by the converter.

The following may be stated in summary:

3.7 Operation on frequency converter with use in Zone 21 (Ex II 2D)

It is mandatory that motors for use in Zone 21 be certifiedby a notified body for operation on the frequency con-verter. It is imperative that the limit values specified on thenameplate and on the EC type-examination certificate are

observed. This also means, in particular, monitoring themotor current depending on the frequency. Only frequencyconverters which meet the requirements stated in the ECtype-examination certificate may be used.

3.8 Operation on frequency converter with use in Zone 1 (Ex II 2G)

It is mandatory that motors of the Increased safety “e” typeof ignition protection for use in Zone 1 are certified by anotified body for operation on the frequency converter. Itis essential that the limit values specified on the nameplateand on the EC type-examination certificate are observed. Inparticular, this means monitoring the continuous current de-

pending on the frequency. Only frequency converters whichmeet the requirements stated on the EC type-examinationcertificate may be used. The thermal winding protectioninstalled must be evaluated by a tripping unit meeting therequirements of Directive 94/9/EC, using the Ex labellingII (2) G. By no means can the specified maximum speedor frequency be exceeded. The maximum permitted pulsevoltage of 1560 V must be limited on the motor terminalsby selecting a suitable converter and/or using filters. It isnecessary to ensure that the operating voltage at the motorterminals complies with the specifications on the nameplate(watch out for voltage drop because of filter!). If the terminalvoltage on the motor is less than the rated voltage specifiedon the nameplate, because of voltage drops caused by thefrequency converter, wiring and possible throttles or filters,

the edge frequency must be set to a lower value correspon-ding to a linear voltage/frequency allocation. This producesa lower possible speed range.



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Figure 3.11: Example of an EC type-examination certificate of Increased safety “e” type of ignition protection foroperation on the frequency converter.

3.9 Permanent-magnet synchronous machines

Synchronous machines as such have been known sincethe beginnings of electrical drive engineering as a machinetype which is used for high-power motors in the form of anexternally excited synchronous motor. All high-power gene-rators in thermal power stations and hydropower stationsare likewise based on this function principle. The normativedemands placed on this machine type are described in thestandard DIN EN 60034-1.

In a permanent-magnet synchronous machine, the DC rotorwinding required to excite the magnetic field is replaced

with permanent magnets. In the field of positioning drives(e.g. robot arms in the automotive industry), permanent-magnet synchronous machines have already representedthe state of the art for several years.

It is generally possible to use permanent-magnet synchro-nous machines and reluctance machines in areas subject

to explosion hazards, but each individual case must beanalysed separately with regard to machine design and thepotential ignition sources, in order to determine the scope oftesting to be performed by the notified body.

The current harmonised standards EN 60079-7 andEN 60079-0 do not address the special requirements ofthese machines in respect of increased safety – type ofignition protection “e”. At IEC level, too, no normativespecifications exist with regard to the testing of permanent-magnet synchronous machines.

Explosion-protected permanent-magnet synchronousmachines and their testing are the subject of a current PTBresearch project.



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4 The VEM product range of explosion-protected equipment4.1 Overview

The extensive range of VEM low voltage motors providesthe chemical industry with a wide selection of explosion-

protected motors of the various types of ignition protectionfor gas and dust explosion-protected areas. The followingtype of ignition protections are included in the range:

Explosion-protected three-phase asynchronousmotors with squirrel-cage rotor for low voltage– Increased safety “e” type of ignition protection

Ex e II complying with EN 60079-0/EN 60079-7– Flameproof enclosure “d/de“

Ex d/de complying with EN 60079-0/EN 60079-1– Type of ignition protection “n”

Ex nA II complying with EN 60079-0/EN 60079-15– Motors for use in areas with combustible dusts

II 2D, II 3D complying with EN 61241-0/ EN 61241-1, EN 60079-0/EN60079-31

– Motors for optional use in gas and dust explosionprotection 2G or 2D, 3G or 2D and 3G or 3D

VEM has been supplying these drives for decades. They are tested and certified by the following bodies:– Physikalisch-Technische Bundesanstalt Braun- schweig (Notified body No. 102),– IBExU Freiberg (Notified body No. 0637) or– DMT Gesellschaft für Forschung und Prüfung mbH

(Notified body No. 0158), now DEKRA EXAM GmbH. These test certificates are recognised by all European Unionmember states. The members of CENELEC who do notbelong to the EU also accept them. In the case of special

designs which affect explosion protection (other frequency,output, coolant temperature, use on the frequency conver-ter, etc.), an additional or new certificate may be necessary.

4.2 Energy efficiency and explosion protection

While the questions of classification of energy-saving mo-tors in Europe used to be settled on a voluntary basis bythe Voluntary Agreement (Degree of Efficiency CategoriesEFF1, EFF2 and EFF3), the latter has now been replacedby EN 60034-30: “Degree of Efficiency Classification of Three-Phase Motors with Squirrel-Cage Rotors, with theException of Pole-Changing Motors (IE Code)”. For 2-, 4-and 6-pole motors in the 0.75 kW – 375 kW output range,this standard specifies the minimum efficiency factors forDegree of Efficiency Category IE1 (standard degree of effi-ciency), IE2 (higher degree of efficiency) and IE3 (premiumdegree of efficiency). It should be noted that the measure-

ment procedures for determining the degree of efficiencyhave changed with the switch to this standard. WhereEN 60034-2, with which the additional losses were calcu-lated across-the-board at 0.5 % of input power, used to beapplied, the new rules provide for EN 60034-2-1 to serveas the basis for determining the degree of efficiency; theadditional losses are calculated by testing, in this case.

In the future, motors for operation in explosive atmos-pheres (EN 60079 and EN 61241) will be included inthe degree of efficiency classification complying withEN 60034-30 (IE1…IE3). This includes all type of ignitionprotections relevant to electrical equipment, such as Flame-proof enclosure “d”, Increased safety “e”, non-sparking“n” and protection by housing “tD A21” and “tD A22”. Admittedly, no minimum degrees of efficiency are appliedto them according to VO No. 640/2009 but energyefficiency will establish itself in this product segment also,because of the requirements of the chemical industry, forexample. From the design point of view, the motors inEx d/de and Ex nA and the dust emission protectiontypes are quite uncomplicated. Compared with the stan-

dard motors, there is no separate size/output allocation;the electrical design is identical. That means thatEN 50347 can be applied in full to these motors. Withthese type of ignition protections, the explosion protec-tion concentrates primarily on special design measuressuch as the use of certified components, special con-nection systems, increased clearance and creepagedistances, questions of electrostatic charge with fansand compliance with certain minimum degrees of IPprotection and questions of materials (especially ageingand temperature resistance of seals). The temperature li-mitation measures on the surfaces of the motors or in the

interiors also do not contradict high degrees of efficiency.For this reason, it has already previously been possible tofind motors in the market with EFF1 degrees of efficiencyin these types of ignition protection.

VEM motors from the WE1R/W21R energy-saving serieswith „Ex nA II“ and protection by housings „tD A21“ and„tD A22“ types of ignition protection have been in theproduct range for a fairly long time. These motors can besupplied as IE2-W…/IE2-KPR/KPER and also as IE3-W…on request. Motors in Flameproof enclosure “d” in SeriesK82R may also be supplied in Categories IE2 (K82R…Y2)and IE3 (K82R…Y3).

The situation is different for the Increased safety “e” typeof ignition protection. Here we have temperature limitationin the case of error, in addition to the measures alreadymentioned. That means special requirements of the start-ing current and a guarantee of t

E times that are as long

as possible. Further to that, the size/output allocation isgoverned in Germany by the DIN 42673 and DIN 42677standards. The active materials in the Increased safety “e”



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series will be the same as those in the standard IE2series in the future. This produces the basic prerequisitesfor observing the new degree of efficiency categories. The IE2-K11R…/ IE2-KPR/KPER… Exe II T3 and

IE3-K11R…/IE3-KPR/KPER… Exe II T3 series have beenproduced. Since these motors are equipment in Category 2(for use in Zone 1), separate EC type-examinationcertificates are necessary for motors in this series.

4.3 Gas-explosion protected motors4.3.1 Motors with squirrel-cage rotor, type of ignition protection –

Flameproof enclosure “d/de”

Type K82R and B82R (-Y2, -Y3) (Y2 corresponds to IE2 design and Y3 corresponds to IE3 design)Sizes 63 – 450

Types of protection IP 55, IP 56, IP 65 complying with EN 60034-5Cooling type IC 411 complying with EN 60034-6Designs IM B3, IM B35, IM B5, IM B14, IM B34 and derived designs complying with EN 60034-7

Ambient temperatures -55 °C to +60 °C Temperature category T3 to T6

Explosion-protected design in accordance with Equipment Group II, Category 2 Ex d(e) EN 60079-0 General Conditions EN 60079-1 Flameproof enclosure “d”Mounting dimensions and power allocation complying with DIN 42673 page 3 or DIN 42677 page 3

Summary of approvals:Series and shaft centres Ex II 2G Ex d(e) IIC T3 – T6 Ex II 2G Ex d(e) IIB+H2 T3 – T6K82. 63 – 71 PTB09ATEX1017 X PTB09ATEX1032 X K82. 80 – 160 PTB09ATEX1018 X PTB09ATEX1033 X K82. 180 PTB09ATEX1019 X PTB09ATEX1034 X K82. 200 PTB09ATEX1020 X PTB09ATEX1035 X K82. 225 – 315 PTB09ATEX1018 X PTB09ATEX1033 X K82. 355 PTB09ATEX1021 X PTB09ATEX1036 X K82. 400 PTB09ATEX1022 X PTB09ATEX1037 X K82. 450 PTB09ATEX1023 X PTB09ATEX1038 X

B82. 80 – 132 PTB09ATEX1039 X

Example of labelling:Ex d IIC T4, new complying with EN 60079-0:2009 (EPL): Ex d IIC T4 Gb (alternatively: Ex db IIC T4)



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4.3.2 Motors with squirrel-cage rotor, type of ignition protection – Increased safety “e”

Type KPR/KPER/IE1-KPR/KPER/IE2-KPR/KPER K1.R/IE1-K1.R/IE2-K1.R/IE3-K1.RSize 56 – 355

Types of protection IP 54, IP 55 and IP 65 complying with EN 60034-5

Cooling type IC 411 complying with EN 60034-6Designs IM B3, IM B35, IM B5, IM B14, IM B34 and derived designs complying with EN 60034-7 For assembling motors in designs with vertical shaft position, it is necessary to prevent foreign

bodies from falling into the ventilation holes (protective cover).Explosion-protected design in accordance with Equipment Group II, Category 2 complying with EN 60079-0 General Conditions EN 60079-7 Increased safety “e”

Temperature categories T1 and T2, T3 or T4Mounting dimensions and power allocation complying with EN 50347 (DIN 42673 page 2 or DIN 42677 page 2)

Ambient temperatures -40 °C to +40 °C, with sizes56 to 112: -20 °C to +40 °C, other values in accord-ance with amendments and appropriate data sheets orsupplementary sheets

The motors’ design is tested by the PTB and by the IBExUInstitut für Sicherheitstechnik GmbH andcertified as follows:

Motor’s mechanical components:EC type-examination certificate IBExU02ATEX1108 UEC type-examination certificate IBExU00ATEX1083 Uincluding Supplements 1 to 11

Terminal boxes:EC type-examination certificate IBExU00ATEX1051 Uincluding Supplements 1 to 6

The EC type-examination certificates listed below are also

available with supplementary sheets on the documentation,for use as intended in explosion areas.

The supplementary sheets on the EC type-examinationcertificate applicable to the individual models can be foundin the approval summary.

Series and shaft centres EC type-examination certificate EC type-examination certificateKPER 56 PTB99ATEX3308 IBExU02ATEX1109KPER 63 PTB99ATEX3309 IBExU02ATEX1110KPER 71 PTB99ATEX3310 IBExU02ATEX1111KPER 80 PTB99ATEX3311 IBExU02ATEX1112KPER 90 PTB99ATEX3312 IBExU02ATEX1113

KPER 100 PTB99ATEX3313 IBExU02ATEX1114KPER 112 PTB99ATEX3314 IBExU02ATEX1115K1.R 112 PTB09ATEX3004/PTB08ATEX3026X IBExU02ATEX1153K1.R 132 PTB08ATEX3037/PTB08ATEX3001X IBExU99ATEX1142K1.R 160 PTB08ATEX3038/PTB07ATEX3142X IBExU99ATEX1105K1.R 180 PTB08ATEX3039/PTB07ATEX3143X IBExU99ATEX1138K1.R 200 PTB08ATEX3040/PTB08ATEX3027X IBExU99ATEX1143K1.R 225 PTB08ATEX3041/PTB08ATEX3028X IBExU99ATEX1144K1.R 250 PTB08ATEX3042/PTB08ATEX3029X IBExU99ATEX1131K1.R 280 PTB08ATEX3043/PTB08ATEX3030X IBExU99ATEX1030K1.R 315 PTB08ATEX3044/PTB08ATEX3031X IBExU99ATEX1137K1.R 355 PTB08ATEX3032X IBExU01ATEX1009

Example of labelling:Ex e II T3, new complying with EN 60079-0:2009 (EPL): Ex e IIC T3 Gb (alternatively: Ex eb IIC T3)



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4.3.3 Motors with squirrel-cage rotor, type of ignition protection – “n”

Type KPER/KPR/IE1-KPR/KPER/IE2-KPR/KPER K1.R/W.1R/IE1-K1.R/IE2-W..R/IE3-W4.RSize 56 – 400

Types of protection IP 54, IP 55, IP 56 and IP 65 complying with EN 60034-5

Cooling type IC 411 complying with EN 60034-6Mounting dimensions and power allocation complying with EN 50347Designs IM B3, IM B35 and IM B5 and derived designs complying with EN 60034-7. For assembling motors in designs with vertical shaft position, it is necessary to prevent foreign

bodies from falling into the ventilation holes (protective cover). Temperature category T2, T3 or T4 Ambient temperatures -40 °C to +55 °C (for sizes 56 – 112: -20 °C to +55 °C)Explosion-protected design in accordance with Equipment Group II, Category 3 EN 60079-0 General Conditions EN 60079-15 type of ignition protection “n”

For the motors’ design, there are the following EC type-examination certificates:Series KPR 56 – 112: IBExU06ATEXB001Series KPR 63 – 132T: IBExU06ATEXB002

Series (IE1-)K1.R 112 – 355: IBExU09ATEXB006Series (IE2-)W.1R 112 – 315: IBExU03ATEXB004

Example of labelling:Ex nA II T3, new complying with EN 60079-0:2009 (EPL): Ex nA IIC T3 Gc (alternatively: Ex nAc IIC T3)

4.4 Dust-explosion protected motors4.4.1 Motors with squirrel-cage rotor for use in the presence of combustible dusts,

Zone 21 Type KPR/KPER/IE1-KPR/KPER/IE2- KPR/KPER K2.Q/IE1-K2.Q/K1.R/IE1-K1.R/IE2-W.1R/IE3-W.4R

Size 56 – 355 Type of protection IP 65 complying with EN 60034-5Cooling type IC 411 complying with EN 60034-6Maximum surface

Temperature 125 °C, other surface temperatures on requestDesigns IM B3, IM B35 and IM B5 and derived designs complying with EN 60034-7 For assembling motors in designs with vertical shaft position, it is necessary to prevent foreign

bodies from falling into the ventilation holes (protective cover).Mounting dimensions and power allocations complying with EN 50347

Ambient temperatures -30 °C to +40 °C (+55 °C), for sizes 56 to 132T: -20 °C to +40 °C (+55 °C)Explosion-protected design in accordance with Equipment Group II, Category 2 EN 60079-0 and EN 61241-0 General Conditions EN 61241-1 protection by housing “tD”

For the motors’ design, there are the following EC type-examination certificates:Series KPER 56 to 132T: DTM00ATEXE012X Series (IE1-)K2.Q 112 – 315: IBExU02ATEX1019Series (IE1-)K1.R 112 – 355: IBExU09ATEX1065Series (IE2-)W.1R 112 – 315: IBExU04ATEX1118

Example of labelling:Ex tD A21 IP 65 T125 °Cnew complying with EN 60079-0:2009 (EPL): Ex tb IIIC T125 °C Db (alternatively: Ex tb IIIC T125 °C)



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4.4.2 Motors with squirrel-cage rotor for use in the presence of combustible dusts,Zone 22

Type KPR/KPER/IE1-KPR/KPER/IE2- KPR/KPER K1.R/K2.R/IE1-K2.R/IE2-W.1R/IE3-W.4RSize 56 – 400

Type of protection IP 55 complying with EN 60034-5 (for combustible dusts IP 65)Cooling type IC 411 complying with EN 60034-6Maximum surface

Temperature 125 °C, other surface temperatures on requestDesigns IM B3, IM B35 and IM B5 and derived designs complying with EN 60034-7, for assembling the motors in designs with vertical shaft position,

foreign bodies must be prevented from falling into the ventilation holes (protective cover)Mounting dimensions and power allocations complying with EN 50347

Ambient temperatures -40 °C to +40 °C, for sizes 56 to 132T: -35 °C to +40 °CExplosion-protected design in accordance with Equipment Group II, Category 3 EN 60079-0 and EN 61241-0 General Conditions EN 61241-1 protection by housing “tD” EN 60079-31 protection by enclosure “t”

The motors’ design is certified by an EC Declaration of Conformity.

Example of labelling:Ex tD A22 IP 55 T125 °Cnew complying with EN 60079-0:2009 (EPL): Ex tc IIIC T125 °C Dc (alternatively: Ex tc IIIC T125 °C)

4.5 Combinations of gas-explosion protection or dust-explosion protection

Depending on the design, the following combinations are possible:1. 2G/2D Ex d(e) II 2G or Zone 21 II 2D IP 65 T200 °C – T85 °C2. 2G/2D Ex e II 2G or Zone 21 II 2D IP 65 T125 °C 3G/2D Ex n A II 3G or Zone 21 II 2D IP 65 T125 °C

3. 3G/3D Ex n A II 3G or Zone 22 II 3D IP 55 T125 °C

With the combined motors 2G/2D and 3G/2D for the K82. series in each case, the ambient temperature islimited to -40 °C to +60 °C, KPER/KPR to -20 °C to +40 °C and to -30 °C to +40 °C for the K1.R series.

There are also the following certificates:

Design of motors 2G/2DSeries K82. 63 – 450: according to the Flameproof enclosure “d” certification summarySeries KPER/KPR 56 – 112: IBExU02ATEX1108 U and IBExU02ATEX1109 to 1115Series K1.R 112 – 355: according to the Increased safety “e” certification summary with additional certificate IBExU09ATEX1065

Design of motors 3G/2DSeries (IE1-)K1.R 112 – 355: IBExU09ATEXB006 in addition to IBExU09ATEX1065

Series (IE2-)W.1R 112 – 315: IBExU03ATEXB004 in addition to IBExU04ATEX1118

Design of motors 3G/3DSeries (IE1-)K1.R 112 – 355: IBExU09ATEXB006 in addition to manufacturer’s declaration Zone 22Series (IE2-)W.1R 112 – 315: IBExU03ATEXB004 in addition to manufacturer’s declaration Zone 22




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5 Maintenance and repair

Maintenance, repair and modifications of explosion-pro-tected machines must be carried out in accordance withthe Operating Safety Guidelines (BetrSichV) and the ProductSafety Act/Explosion Protection Ordinance (ProdSG/

11. ProdSV) in Germany.

In order to guarantee the safe operation of the system,consisting of the drives and the matching monitoring de-vices, through the total period of use of the technical system,a regular inspection of the equipment and, if necessary re-pair/replacement must be carried out. In this case it is in theoperator’s responsibility to ensure the equipment’s propermaintenance and upkeep. As regulations for this purpose,the Operating Safety Guidelines and StandardEN 60079-17 must be named.

With the increasing testing intensity in the tests, the distinc-tion is drawn between visual inspection, close inspectionand detailed examination. A visual inspection can be carried

out while the machine is running and often just in passing,during a walk through the plant. A visual inspection meanslooking over the equipment without using any aids toaccess it. By this means it is possible to detect a missing ordamaged terminal box lid on the machine but also to recog-nise noticeable bearing noises. In the case of a close in-spection, the housing is subjected to a detailed inspection,e. g. with the help of a ladder, or the bearing temperature ismeasured with an infrared thermometer. Generally speaking,taking the machine out of service is not necessary.

For the detailed inspection, the machine is shut downand subjected to tests such as measurement of insulationresistance. The various tests can be clearly displayed in the”Testing Pyramid”.

Figure 5.1: Testing Pyramid

Outside of Germany, the relevant national regulationsmust be observed.

Further instructions for testing and upkeep of electrical

systems or the repair and repair of electrical equipment aregiven in EN 60079-17 and EN 60079-19. Tasks affectingexplosion protection are considered as such, for example:– Repairs to the stator winding and the terminals– Repairs to the ventilation system– Repairs to the bearings and the seals in the case of dust-explosion protected motors (Ex 2D, 3D) may be

carried out only by the manufacturer’s service personnelor buyers/in authorised workshops by qualified person-nel which has the necessary knowledge acquired fromtraining, experience and instruction.

In the case of dust-explosion protected motors, dust-ex-plosion protection depends very heavily on local conditions.For this reason, the motors in these areas must be regularlytested and serviced.

Because of thermal insulation, thick layers of dust result ina rise in temperature on the motor’s surface. Dust depositson motors or indeed the motors being covered completelymust thus be prevented by suitable fittings and ongoingmaintenance.

The specified motor surface temperature is only valid if thedust deposits on the motor do not exceed a thickness of5 mm. There must be a guarantee that these initial conditions(type of dust, maximum layer thickness etc.) are assured.

The motor must not be opened before a sufficiently longtime has passed, to allow the internal temperatures to diedown to values which are no longer combustible. If themotors have to be opened for maintenance or repairs, these

tasks must be completed wherever possible in a dust free-environment. If this is not possible, suitable measures mustbe taken to prevent dust from entering the housing. In thecase of dismantling, particular care must be taken to ensurethat the components necessary for imperviousness of thestructure, such as seals, end faces etc. are not damaged.

Careful, regular maintenance, inspections and checks areessential in order to detect any faults in time and to remedythem before consequential damage occurs. Since the op-erating conditions cannot be precisely defined, only generaldeadlines, with the prerequisite of fault-free operation, canbe given. They must always be adapted to the local condi-tions (pollution, stress etc.).

Recommended values, manufacturer-dependent

What is to be done? Time interval Recommended deadlinesInitial inspection After approx. 500 operating hours After six months at the latestChecking motor’s air supplyand surface Depending on degree of local pollutionLubrication (optional) See nameplate or lubrication plateMain inspection Approx. 10000 operating hours Once annuallyDrain condensate Depending on climatic conditions

T i m

e d e v o

t e d t o

t e s t i n

g T e s t i n g f r e q u e n c y

V i s u a l

C l o s e -

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D e t a i lD e t a i l

C l o s e - u p

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The necessary lubrication times for anti-friction bear-ings must be observed according to manufacturer’sspecifications.

Maintenance tasks (except for lubrication tasks) must beperformed only when the machine is shut down. It must

always be ensured that the machine is safeguarded againstbeing switched on and labelled with a suitable warning sign. Also, the particular manufacturers’ safety instructions andaccident prevention regulations must be heeded for the useof oils, lubricants and cleaning agents! Adjacent compo-nents which are live must be covered!

It must be ensured that the auxiliary circuits, e. g. shutdownheaters, are dead. In the case of the design with conden-sate drain hole, the drain plug must be smeared with suit-able sealant (e. g. Epple 28) before it is closed again!

If the tasks are not performed by the manufacturer, theymust be performed by suitably-qualified personnel andtested by a “Qualified, Officially-Recognised Person” (in the

case of the repair’s relevance to explosion protection). Thatperson must issue a written confirmation or attach a testmark to the machine. Tests undertaken in accordance withSection14, paragraph 6 of the Operating Safety Guidelines

must be documented in accordance with Section 19 ofthe Operating Safety Guidelines. The documentation mustshow that the device, protection system and safety, controlor regulation devices correspond to the requirements of theOperating Safety Guidelines after the repair. It is recom-mended to retain the documentation beyond the device’s

period of use and to clearly label the device for the sake oftraceability.

Important: The operator is responsible for operating asystem requiring monitoring. This also includes the repair ofequipment and protective systems. Abroad, therelevant national regulations must be observed.

Spare partsWith the exception of standardised, commercially availableand similar standard components (e. g., anti-friction bear-ings) only genuine spare parts (see manufacturer-specificspare part lists) may be used; this particularly applies also toseals and connection parts.

The following details are essential for ordering spare parts:– Spare part designation– Motor model– Motor number

6 Repair and modification of electrical equipment6.1 General

The legal basis for operation of explosion-protected electricalequipment in explosion hazard areas is the 11th Ordinanceto the Product Safety Act (Explosion Protection Ordinance) –11. ProdSV, in conjunction with the Operating Safety

Guidelines (BetrSichV).

Previously applicable guidelines such as the“Guidelines on Electrical Systems in Explosion Hazard

Areas (ElexV)“ have thus lost their validity.

Further requirements are contained in the StandardEN 60079-14 and in the Explosion Protection Regu-lations BGR 104. A modification to a system requiringmonitoring, in the sense of the Operating Safety Guidelines,is considered to be any procedure which affects thesystem’s safety. A modification is also considered to be anyrepair which affects the system’s safety. A considerablemodification to a system requiring monitoring in the senseof the Operating Safety Guidelines is considered to be any

modification which changes the system requiring moni-toring to the extent that it corresponds to a new system,where safety features are concerned. Under the designationof Maintenance and Repairs comes a combination of allthe tasks which are performed to maintain an object in acertain state or to restore it to that state which meets therequirements of the object in question and guarantees theperformance of the required functions.

The following form the basis of this:– EN 60079-17, Testing and upkeep of electrical systems

and– TRBS 1201 “Testing of work equipment and systems

requiring monitoring”– TRBS 1201 Part 3 “Repairs to equipment, protection

systems etc.”

They are provided for operators and deal with the pointsof view which are directly related to testing and upkeep ofelectrical systems in explosion risk areas. The operator mayhave explosion-protected equipment repaired in any work-shop of his choice. If parts on which explosion protection

depends are replaced or repaired, there must be a test byan officially recognised qualified person before recommis-sioning.

(A qualified person in the sense of the Operating SafetyGuidelines is a person who has the necessary specialistknowledge to test the work equipment on the basis of theirprofessional training, their professional experience and theirrecent professional activities.

The requirements of the qualified person are explainedin the guide to the Operating Safety Guidelines and in

TRBS 1203. In accordance with Section 14, paragraph 6 ofthe Operating Safety Guidelines, qualified persons can beofficially recognised by the appropriate ministry – thisvaries from state to state.

Recognition as a qualified person is company-related andapplies only to tests of such equipment, protection sys-

tems and safety, control and regulation devices which thiscompany has repaired. Recognition does not apply to alltests on equipment, protection systems and safety, controland regulation devices which have been repaired within thecompany regarding a part on which explosion protectiondepends but only to tests complying with repair proceduresfor which the recognition application has been made andwhich are listed in detail in the approval document).

The technical regulations for repair and maintenance ofequipment in explosion hazard areas are defined in Stan-dard EN 60079-19. It constitutes a guideline which providesinstructions of a technical nature on repair and the repair,regeneration and modification of certified equipment andwhich has been designed for use in explosion hazard areas.

The objective is instruction on practical measures formaintaining the safety of the equipment, the definitionof the requirements which must be set of the function ofequipment that has been repaired and the description ofprocedures necessary for that, so that the equipment alsocontinues to satisfy all relevant regulations after a repair. In



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the case of the various ignition types, examples are givenon repair, maintenance and overhaul as well as possiblemodifications to explosion-protected electrical equipmentand the necessary tests for them are described.

After repair the equipment is accepted as complying with

the EC type-examination certificate if manufacturer-prescri-bed components have been used.

In the event that the certification documents are not availa-ble or available to an inadequate extent, the repair must becarried out on the basis of EN 60079-19 or the correspondingrelevant standard (EN 60079...). If more detailed types ofrepair or modification are applied, which do not conform tostandards, it must be decided on the part of the manufacturer

or the certifying authority (notified body) whether this equip-ment is suited to continued use in explosion hazard areas.

6.2 Repair tasks not affecting the explosion protection

Replacement of the following:– Bearings– Motor feet (if possible)– Terminal box (parts)– Replacement of the seals by genuine parts– Inlet part– Terminal board– Fan/fan cover

– End shields

Design conversions from:– IM B3 to IM B35 and IM B34

– IM B3 to IM B5 and IM B14– Terminal box (parts)– IM B35 to IM B5 and IM B14– Attaching and removing feet (if possible)

Cleaning:– Sealing surfaces– Seals

Generally speaking, genuine spare parts must be used. Theuse of non-genuine, but Ex-tested parts is legally permis-sible but automatically voids the manufacturer’s guarantee.

6.3 Repair tasks requiring inspection by an officially-recognized, qualified person

– Repairing or renewing winding(winding information according to manufacturer)

– Reworking size and number of inlet holes– Renewal of parts in ventilation system– Replacement of the seals by parts that are not

genuine but with Ex-test results

– Reconditioning motor and stator without significantlyincreasing the air gap

Repairing or renewing the winding must only be doneaccording to manufacturer’s information (winding data/ materials). In the case of insulating material parts beingreplaced by parts from another insulating material and/or ofdifferent dimensions, the guarantee is automatically voided.

6.4 Repair tasks on Ex e motors (modifications) which require a new type approval

(e. g. by a notified body according to RL 94/9/EC)

– Installation of different/additional parts in the device (mainterminals, auxiliary terminals or additional equipment)

– Reconditioning rotor and stator– Winding for a different voltage– Renewing ventilation system parts (e. g. fan wheel)– Rewinding for a different speed

– Changing gap sizes

These tasks may be performed under the above-mentionedcondition. VEM, however, allows these tasks, for example,only in the manufacturing factories. If they are performedin a workshop, the guarantee is automatically voided!



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6.5 Repair tasks on Ex d motors (modifications) which require a new type approval

(e. g. by a notified body according to directive 94/9/EC)

– Installing additional components in the machine– Reconditioning sparkover-prevention gap

– Reconditioning rotor and stator– Regenerating components which are not part of theFlameproof enclosure

– Renewing ventilation system parts (e. g. fan wheel)– Regenerated components must pass the appropriate

overpressure test

– Rewinding for a different speed or voltage– Changing the gap size

– Modifications to the ventilation system

These tasks may be performed under the above-mentionedcondition. VEM, however, allows these tasksonly in the manufacturing factories. If they are performedin a workshop, the guarantee is automatically voided!

6.6 Summary

By and under theScheduling the tasks With use of responsibility ofto be performed Standard part Genuine Trained Manufac- spare part experts turing factory

Replacement of the following:– Bearings X X X X – Motor feet (if possible) - X X X – Terminal box (parts) - X X X – Terminal board X X X X – Inlet part - X X X – Fan/fan cover - X X X – End shields - X X X – Rotor - X X X Conversion of– IM B3 to IM B35 and IM B34 - X X X – IM B3 to IM B5 and IM B14 X X X – IM B35 to IM B5 and IM B14 X X X – Attaching and removing feet

(if possible) - X X X

Cleaning of– Sealing surfaces - X X X – Seals - X X X Reconditioning and revising of– Air gap - - 0 X – Number and/or size

of inlet holes - - X X Fitting other/additional– Main terminals 0 0 0 X – Auxiliary terminals - X X X Replacement winding – Stator - - X X – TMS - - X X – Stator together with wound core - X X X Winding according to

manufacturer’s specifications - - X X Winding for– different number

of poles/frequencies - - 0 X

7 Testing the motors after repairs, maintenance or modifications

After repairs, maintenance or modifications the motors mustundergo a test in accordance with Section 10 of the Operat-ing Safety Guidelines (BetrSichV) dated 3rd October 2002.

This test may be performed only by persons qualified to doso. The test must satisfy the requirements in accordancewith DIN IEC 60079-19.

The tests below must be performed and documented:

Visual check of winding and of the complete motor, takingthe increased safety requirements particularly into account.



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7.1 Visual check7.1.1 Visual check of winding – main points

– Check of winding overhang– Bandages

– Slot and phase insulation– Slot wedges– Wire insulation

7.1.2 Visual check of complete motor – main points

– Terminal marking– Terminal connectors properly connected– Cable glands– Seals– Fan assembly– Fan cover fastening

7.2 Winding test7.2.1 Winding resistance

The ohmic DC resistances are supplied by supplying themotor winding with a constant current via two terminals ineach case and the voltage drop is measured on the motorterminals. The resistance between the U-V, V-W and U-Wterminals is calculated on this basis. In addition, the windingtemperature is measured.

On the test certificates, the winding’s winding resistance isshown at 20 °C. For this purpose, the measurements mustbe converted at temperatures deviating from 20 °C.

7.2.2 High-voltage test The winding’s insulation resistance is tested by the high-voltage test.

EN 60034-1 or VDE 0530 Part 1 prescribes the followingprocedure for testing machines with a rated voltage≤ 1 kV:

The voltage test must be performed between the windingsfor testing and the motor housing. The stator core is con-nected to the windings or phases (e. g. V1 and W1) whichare not provided for testing and the test voltage is appliedbetween housing and U phase. The motor is thus testedsimultaneously for short-circuit to the exposed conductive

part and for inter-phase short-circuit with one measurement.

The high-voltage test is performed on the impregnated andfully-assembled motor by a mains-frequency and,as much as possible, sinusoidal test voltage, with an RMSvalue of 2*UN

+ 1000 V complying with EN 60034-2. Thetest should be started at a maximum voltage of half of the fulltest voltage and then increased, within at least 10 seconds,constantly or in maximum steps of 5 % of the final value.

The full test voltage must be maintained for 1 minute. A repeat test may be performed only at 80 % of the maxi-mum test voltage. Windings already in use are tested for aninspection, for example, at a minimum of 1000 V.

7.2.3 Insulation value (insulation resistance)

On initial commissioning and especially after fairly lengthystorage, the winding’s insulation resistance must bemeasured for earthing and between the phases. The testmust be performed at rated voltage and at least at 500 V.Dangerous voltages occur on the terminals during andimmediately after measurement. On no account touch ter-minals and carefully heed operating instructions for insula-tion measuring unit! Depending on the rated voltage U

N, the

following minimum values must be observed at a windingtemperature of 25 °C:

Rated power Insulation resistanceP

B related to rated voltage

kW k Ω /V 1 < P

B ≤ 10 6.3

10 < PB ≤ 100 4

100 < PB 2.5

If the minimum values are not reached, the winding must beproperly dried until the insulation resistance corresponds tothe required value.



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7.3 Test run7.3.1 Rotating field (direction of rotation check)

The direction of rotation check ensures that the direction ofrotation is to the right, looking towards the drive side, when

7.3.2 No-load test, detection of no-load current I0 The no load test is used for checking the winding number,the circuit and evaluating the running properties. It isperformed when the engine is cold, at a rated voltage of±1%. The machine is completely unloaded (disconnectedfrom the load machine). During the measurement, voltage,currents and outputs are recorded.

The power consumption is measured in all the phases andcompared with the manufacturer’s specifications.

The permitted tolerance – related to the manufacturer’sspecification – is ±15 %. Furthermore, the no load currentsin the three phases may also differ from one another only bya maximum of 15 %.

7.3.3 Evidence of phase symmetry

7.3.3.1 Short-circuit tests with IB

The stator winding of motors with squirrel-cage rotor mustbe supplied by an accordingly reduced voltage, when therotor is locked, in order to reach the full load rated currentand to guarantee the balance of all the phases.

The test is applied as an alternative to the full load test, inorder to prove the undamaged nature of the winding andthe air gap and in order to detect damage on the rotor.Imbalances deviating by less than 5 % from the mean valueare permitted.

7.3.3.2 Short-circuit test complying with EN 60034-1

The short-circuit test is used to determine therelation I

A /I

N.

The rotor is braked, the stator winding is connected to thevoltage and the power consumption measured. If this testis not performed at rated voltage, the initial starting currentI A must be converted in the ratio of the rated voltage to the

test voltage.

In addition to that, a saturation factor of the iron must betaken into account in the case of reduced test voltage.

The ratio I A /I

N calculated in this way may differ from the

nameplate specification by up to 20 %.

Initial starting current I A

(only with Increased safety “e”type of ignition protection) saturation factor f

s for conversi-

ons in the case of reduced test voltage with locked rotor(1) Rotor with slots completely or almost closed

(2) Rotor with open slots

Target value for initial starting current I A = I

N . I

A /I

Na) Test voltage = rated voltage U

N Test current’s permitted deviation: ± 20 % from I

A (essential to observe minus tolerance for stator

and rotor winding test)b) Test voltage U

x Test voltage I

x

Reduction ratio R = Ux /U

NSaturation factor f

S

Test current converted to rated voltageIKN

= Ix . f

S /R

Permitted deviation for the convertedtest current:IKN

: ± 10 % of I A

If the original insulation system and/or paint system is/arenot available, the t

E time must be checked according to

EN 60079-7. Copying the winding is not permitted until thetE time has been checked against Equipment Standard

EN 60079-7.

Figure 7.1: Saturation factors as dependent on the ratio oftest voltage to rated voltage

the mains wiring is connected to U, L2 to Vand L3 to W.

1

1.05

1.1

1.15

1.2

1.25

1.3

1.351.4

1.45

1.5

0 0.2 0.4 0.6 0.8 1

1

2

U / UN

f s



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7.4 Painting and impregnation after repair work

The repainting of an explosion-protected motor or the im-pregnation of a complete stator after re-winding may resultin thicker paint or resin layers on the machine surface. Thiscould lead to electrostatic charging, with a correspondingrisk of explosion in case of discharge. Charging processesin the immediate surroundings could similarly produce anelectrostatic charge on the surface or parts of the surface,and likewise bring a risk of explosion in case of discharge.It is thus imperative to observe the stipulations of IEC/EN60079-0: “Equipment – General requirements”, section 7.4,

and TRBS 2153, e.g. by:

limiting the total paint or resin layer thickness in accordancewith the explosion group– IIA, IIB: Total layer thickness ≤ 2 mm– IIC: Total layer thickness ≤ 0.2 mm

limiting the surface resistance of the paint or resin used– IIA, IIB, IIC, III Surface resistance ≤ 1GΩ for motors of

groups II and III

Breakdown voltage ≤ 4 kV for explosion group III (dust only,measured according to the thickness of the insulation mate-rial using the method described in IEC 60243-1).

In addition, due attention should be given to the contentsof E DIN EN 60079-32: “Electrostatic hazards”, in particular

Annex A: “Basics of static electricity”, Annex B: “Electrosta-tic discharges in special situations” and Annex C: “Combu-stibility of materials”.

7.3.4 Vibration test

To evaluate the quiet running a vibration test according toEN 60034-14 (VDE 0530 part 14):2004 has to be done. Thelimit values of class A or B must be kept in accordance withthe requirements.

Step A (for motors without special vibrationrequirements)Step B (for motors with special vibrationrequirements)



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7.5 Test Documentation

The test results must be documented in a test report.

VEM motors GmbH sample certificate

below: Alternative: ZVEH test certificate

The test reports’ archiving period is 10 years. The report’sconformity to regulations is checked by an officially recog-nized, qualified person.

Published by:Zentralverband der Deutschen Elektro- und Informations-technischen Handwerke (ZVEH)

Available from: www.wfe-shop.de



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8 Summary of standards and regulations8.1 General standards

Heading International Europe Germany IEC – International EN – CENELEC DIN / VDE

Electrotechnical European German IndustrialCommission Committee for Standard/Association Electrical of German

Standardisation ElectriciansRotating electrical machines IEC 60034-1 EN 60034-1 DIN EN 60034-1/ Measurement and operating performance VDE 0530-1Method for determining losses and efficiency IEC 60034-2-1 EN 60034-2-1 DIN EN 60034-2-1/ from tests for rotating electrical machines

IEC 60034-2 EN 60034-2 VDE 0530-2-1 DIN EN 60034-2 /

VDE 0530-2Efficiency classes of single-speed, IEC 60034-30 EN 60034-30 DIN IEC 60034-30cage-induction motors VDE 0530-30Degree of protection provided by the integral design IEC 60034-5 EN 60034-5 DIN EN 60034-5 / of rotating electrical machines (IP Code) VDE 0530-5

– IntroductionMethods of cooling (IC Code) IEC 60034-6 EN 60034-6 DIN EN 60034-6 / VDE 0530-6Classification of types of construction, mounting IEC 60034-7 EN 60034-7 DIN EN 60034-7/ arrangements and terminal box position (IM Code) VDE 0530-7

Terminal markings and direction of rotation IEC 60034-8 EN 60034-8 DIN EN 60034-8 / VDE 0530 Part 8Noise limits IEC 60034-9 EN 60034-9 DIN EN 60034-9 / VDE 0530-9Starting performance of single-speed three-phase IEC 60034-12 EN 60034-12 DIN EN 60034-12 / cage-induction motors VDE 0530 Part 12Mechanical vibrations of certain machines IEC 60034-14 EN 60034-14 DIN EN 60034-14 / with shaft heights 56 mm and higher; measurement, VDE 0530-14evaluation and limits of vibration severityBalance quality ISO 1940 - DIN ISO 1940 /

VDE 0175IEC standard voltages IEC 60038 - DIN IEC 60038Electrical insulation – Thermal evaluation IEC 60085 - DIN IEC 60085 / and designation VDE 0301-1Dimensions and output series for rotatingelectrical machines IEC 60072-1 EN 50347 DIN EN 50347



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8.2 Standards for gas explosion protection

IEC standard Topic Previous Harmonised nomenclature European Standard IEC proposalsIEC 6009-0 General requirements EN 50014/VDE 0170-1 EN 60079-0: 2009(06) IEC 31G / 813 / CDV (6.Ed.)IEC 60079-1 Flameproof

enclosure “d” EN 50018/ VDE 0170-9 EN 60079-1:2007(04) IEC 31/884/CD (7.Ed.)IEC 60079-2 Pressurized enclosure “p” EN 50016:2002 EN 60079-2:2007(04) IEC 31/890/CD (6.Ed.)IEC 60079-5 Powder filling “q“ EN 50017:1998 EN 60079-5:2007 IEC 60079-6 Oil immersion “o“ EN 50015:1998 EN 60079-6:2007 IEC 60079-7 Increased safety “e” EN 50019:2000 EN 60079-7:2007 IEC 31/799 / DCIEC 60079-10 Zone classification VDE 0165/Part 101 EN 60079-10-1:2009(G) VDE 0165/Part 102 EN 60079-10-2:2009(D) IEC 31J/181 / DCIEC 60079-11 Intrinsic safety “ia/ib” EN 50020:1999 EN 60079-11-2012IEC 60079-14 Selection and setup VDE 0170/Part 13 VDE 0165/Part 1 EN 60079-14:2008(03) IEC 31J/178/DC (4.Ed.)IEC 60079-15 Type of ignition protection “n” EN 50021:1999 EN 60079-15:2010(05) TC31/ WG32IEC 60079-17 Testing and maintenance VDE 0170/Part 110 VDE 0165/Part 109 EN 60079-17:2007 IEC 31J/177/CD (4.Ed.)IEC 60079-18 Encapsulation “m” EN 50028:1987 EN 60079-18:2009(04) IEC 31/852/MCRIEC 60079-19 Repair VDE 0165/Part 20-1 EN 60079-19-2011

IEC 60079-25 Intrinsically safe systems VDE 0170/Part 10-1 EN 60079-25:2010 “SYST” EN 50039:1980 EN 50394-1:2004(M)IEC 60079-26 Category 1G Equipment EN 50284:1999 EN 60079-26:2007(Ga) VDE 0170/0171T12-2 EN 50303:2000 (M1) IEC TC30 WG30IEC 60079-27 FISCO/FNICO field bus systems - EN 60079-11:2012 IEC 60079-28 Optical radiation - EN 60079-28:2007 Ak241.0.18 (DKE)IEC 60079-30-1 Electrical EN 62086-1:2005 EN 60079-30-1:2007 resistance heaters EN 62086-2:2005 EN 60079-30-2:2007

Source: Dipl.-Ing. Götze, “Normenstand für elektrische Betriebsmittel in explosionsgefährdeten Bereichen”,IEBxU Freiberg

8.3 Standards for dust explosion protection and other

IEC Standard Topic Superseded Harmonised Standard referring Standard European Standard to EPLIEC 61241-0 General requirements (EN50014+A1+A2:2000) EN 61241-0:2006→ EN 60079-0:2009 (5.Ed.)IEC 61241-1 Protection by housing EN 50281-1-1:2998 EN 61241-1:2004→ EN 60079-31:2009IEC 61241-2-1 Minimum ignition

temperatures VDE 0170/0171 Part 15-2-1 EN 50281-2-1:1998 EN 60079-34-1:200X IEC 61241-2-2 Electrical resistance VDE 0170/0171 Part 15-2-2 EN 61241-2-2:1996 EN 60079-34-2:200X IEC 61241-2-3 Minimum ignition energy VDE 0170/0171 Part 102 EN 13621:2002 EN 60079-34-3:200X IEC 61241-4 Pressurisation VDE 0170/0171 Part 15-4 EN 61241-4:2006→ EN 60079-2:2007IEC 61241-10 Zone classification EN 50281-3:1998 EN 61241-10:2004 EN 60079-10-2:2009IEC 61241-11 Intrinsic safety VDE 0170/0171 Part 15-5 EN 61241-11:2006→ IEC 31G/198/CDV (6.Ed.)IEC 61241-14 Selection and installation EN 50281-1-2:1999 EN 61241-14:2004 EN 60079-14:2008IEC 61241-17 Testing/maintenance (EN 50281-1-2:1999) EN 61214-17:2005 EN 60079-17:2007IEC 61241-18 Encapsulation - EN 61241-18:2004→ EN 60079-18:2009

IEC 61241-19 Repair - EN 61241-19:2003 EN 60079-19:2007IEC 61508-ff Functional safety Parts of ExTAGWG081 IEC 61508-1 to 7 EN 50495:2010 IEC 65A/548 to 554/FDISISO 80079-ff Non-electrical equipment Revision of EN 13463-1 ISO/IEC 80079-36 (1.Ed) EN 1127-1 xxx prEN 1127-1 WD:2010IEC 62013-1 EN 62013-1:2000 EN 62013-2:2006 E DIN IEC 60079-35-1:2009IEC 62013-2 Head torches for mining EN 620013-1:2006 EN 620013-3:2006 IEC 31/885/CDV (2.Ed.)

Source: Dipl.-Ing. Götze, “Normenstand für elektrische Betriebsmittel in explosionsgefährdeten Bereichen”,IEBxU Freiberg



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9 Tolerances9.1 Electrical parameters

These tolerances are approved for three-phase asynchro-nous motors, taking into account necessary manufacturingtolerances and material deviations in the materials used forthe guaranteed values. In the standard, the following notesare provided on this:1. A guarantee of all or any of the values in the table is not

necessarily provided. In quotes, guaranteed values towhich permitted deviations should apply must be named

specifically. The permitted deviations must correspond tothe table.2. Your attention is drawn to the differences in interpretation

of the term “guarantee”. In some countries a distinction ismade between typical or declared values.

3. If the permitted deviation applies only in one direction, thevalue in the other direction is not restricted.

9.2 Mechanical parameters – normal tolerances

In accordance with DIN EN 60034-1 the following tolerances are permitted:

Efficiency -0.15 (1-η) at PN ≤ 150 kW -0.1 (1-η) at PN > 150 kW

Power factor 1-cosϕ minimum 0.02 6 maximum 0.07Slip +

- 20 % at PN ≥ 1 kW(with rated load at operating temperature) +

- 30 % at PN < 1 kWInitial starting current +20 %(in the starting circuit provided) without downward limitationStarting torque -15 % and +25 %Pull-up torque -15 %Breakdown torque -10 % (after applying this tolerance M

K / M

Nstill at least 1.6)

Inertia torque +- 10 %Noise intensity (test surface sound pressure level) +3 dB (A)

Measurement

abbreviationaccording toDIN 42939 Fit or tolerance Meaninga Clearance of the housing foot attachment holes in axial direction +- 1 mma

1 Flange diameter or width - 1 mm

b Clearance of housing foot attachment holes at right angles to the axial direction +

- 1 mmb

1 Diameter of flange’s centring spigot up to diameter 230 mm j6

from diameter 250 mm h6d, d

1 Diameter of cylindrical shaft end up to diameter 48 mm k6

from diameter 55 mm m6e

1 Flange’s hole circle diameter +

- 0.8 mmf, g Motor’s greatest width (without terminal box) +2 %h Shaft centre (lower edge of foot to centre of shaft end) to 250 mm -0.5 over 250 mm -1

k, k 1 Motor’s total length +1 %p Motor’s total length (lower edge of foot,

housing or flange to motor’s highest point) +2 %s, s

1 Diameter of attachment holes in foot or flange +3 %

t, t1 Lower edge of shaft end to upper edge of parallel key +0.2 mm

u, u1 Parallel key width h9

w1, w

2 Distance between centre of first foot attachment hole

and shaft collar or flange surface +- 3.0 mm

Distance from shaft collar to flange surface with D-side fixed bearing +- 0.5 mm

Distance from shaft collar to flange surface +- 3.0 mm

m Motor dimensions -5 to +10 %

Normal shaft end fitsShaft ends up ∅ 48 k6 from ∅ 55 m6Mating components H7



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List of source material

List of source material

RICHTLINIE 94/9/EG DES EUROPÄISCHEN PARLAMENTSUND DES RATESvom 23. März 1994 zur Angleichung der Rechtsvorschriftender Mitgliedstaaten für Geräte und Schutzsysteme zur be-

stimmungsgemäßen Verwendung in explosionsgefährdetenBereichen

RICHTLINIE 1999/92/EG DES EUROPÄISCHEN PARLA-MENTS UND DES RATESvom 16. Dezember 1999 über Mindestvorschriften zur

Verbesserung des Gesundheitsschutzes und der Sicherheitder Arbeitnehmer, die durch explosionsfähige Atmosphä-ren gefährdet werden können (Fünfzehnte Einzelrichtlinie imSinne von Artikel 16 Absatz 1 der Richtlinie 89/391/EWG)

ATEX-Leitlinien, 2. Ausgabe, 07/2005 Aktuelle deutsche Fassung 08/2008

Verordnung über Sicherheit und Gesundheitsschutz bei der

Bereitstellung von Arbeitsmitteln und deren Benutzung beider Arbeit, über Sicherheit beim Betrieb überwachungs-bedürftiger Anlagen und über die Organisation des be-trieblichen Arbeitsschutzes (Betriebssicherheitsverordnung– BetrSichV) Ausfertigungsdatum: 27.09.2002

Leitlinien zur Betriebssicherheitsverordnung (BetrSichV),2. überarbeitete, Auflage 2006

Explosionsschutz-Regeln BGR 104Sammlung technischer Regeln für das Vermeiden derGefahren durch explosionsfähige Atmosphäre mit Beispiel-sammlung, Ausgabe Januar 2007

EN 60079-0: Elektrische Betriebsmittel für gasexplosions-

gefährdete Bereiche – Teil: 0 „Allgemeine Anforderungen“;Beuth-Verlag Berlin, März 2010

EN 60079-1: Explosionsfähige Atmosphäre – Teil 1: Geräteschutz durch druckfeste Kapselung „d“;Beuth-Verlag Berlin, April 2008

EN 60079-2: Explosionsfähige Atmosphäre – Teil 2: Geräteschutz durch Überdruckkapselung „p“; Beuth- Verlag Berlin, Juli 2008

EN 60079-7: Explosionsfähige Atmosphäre – Teil 7: Geräteschutz durch Erhöhte Sicherheit „e“;Beuth-Verlag Berlin, August 2007

EN 60079-14: Explosionsfähige Atmosphäre – Teil 14: Projektierung, Auswahl und Errichtung elektrischer Anlagen; Beuth-Verlag Berlin, Mai 2009

EN 60079-15: Elektrische Betriebsmittel für gasexplo-sions-gefährdete Bereiche – Teil 15:Konstruktion, Prüfung und Kennzeichnung von elektrischen Betriebsmitteln der Zündschutzart „n“; Beuth-Verlag Berlin,Februar 2011

Friedl, W. J.: Ökologische und ökonomische Bedeutung desBrand- und Explosionsschutzes,

Verlag Kohlhammer, 1998

PTB-Prüfregel: Explosionsgeschützte Maschinen derSchutzart Erhöhte Sicherheit „e“ Ex e, Band 3,zweite Ausgabe 2007

PTB-Merkblatt zum Schutz von Asynchronmaschinen bei Anlauf mit verminderter Spannung, Sicherstellung des Ex-plosionsschutzes, AG 3.72, April 2009

Lehrmann, C., Pape, H., Dreger, U., Lienesch, F.: Umrich-tergespeiste Antriebe – ein neuartiges Schutzkonzept für

Antriebe in explosionsgefährdeten Bereichen; Ex-Zeitschrift R.Stahl Schaltgeräte GmbH, Heft 38/2006, S. 36 – 47

Lehrmann, C. : Über ein Zulassungsverfahren für explosions-geschützte, umrichtergespeiste Käfigläufer der ZündschutzartErhöhte Sicherheit „e“; Dissertation Leibniz-Universität Han-nover 2006; erschienen im Shaker-Verlag, Aachen

Elektrische und nichtelektrische Geräte für den Einsatz inexplosionsgefährdeten Bereichen,Dipl.-Ing. (FH) Burkhard Hille / Dipl.-Ing. Kai WillamowskiIBExU Institut für Sicherheitstechnik GmbH, Freiberg

Instandsetzung und Änderung von explosions-geschützten elektrischen Betriebsmitteln,Dipl.-Ing. (FH) Burkhard Hille, IBExU Institut für Sicherheits-technik GmbH, Freiberg

Druckfest gekapselte Motoren für Gas- und Staubexplosi-onsschutz, W. Sobel, ATB Motorentechnik GmbH

Dokumentation nach 94 / 9 / EG aus Sicht eines Anwenders,Dr.-Ing. H. Oberhem, Bayer Industry Services

Normen für explosionsgeschützte elektrische Betriebsmittelim Wandel, Vortrag zum 7. Technischen Tag der VEM- Grup-pe 2008, Dr.-Ing. F. Lienesch, PTB Braunschweig

Staubexplosionsgeschützte elektrische Betriebsmittel– was erwartet uns durch neue IEC-Normen, Vortrag zum7. Technischen Tag der VEM-Gruppe 2008,Dr.-Ing. Michael Wittler, DEKRA EXAM GmbH, Bochum

Explosionsgeschützte Drehstrommotoren und die neuenNormspannungen von U. Engel und H. Wickboldt,PTB Braunschweig

Normungsstand elektrischer Betriebsmittel Elektrische Be-triebsmittel für Gas- + Staubexplosionsgefährdete Bereichevon Dipl.-Ing Götze, IBExU Institut für SicherheitstechnikGmbH, Freiberg

Elektrische Betriebsmittel für StaubexplosionsgefährdeteBereiche von Dipl.-Ing Götze, IBExU Institut für Sicherheits-technik GmbH, Freiberg

TRBS 1201 (September 2006)

Teil 1 Prüfung von Anlagen in explosionsgefährdetenBereichen und Überprüfung von Arbeitsplätzen in explo-sionsgefährdeten BereichenBAnz. Nr. 232a, S. 20 v. 9.12.2006

TRBS 1201 (Februar 2009) Teil 3 Instandsetzung an Geräten, Schutzsystemen, Sicher-heits-, Kontroll- und Regelvorrichtungen im Sinne der Richt-linie 94 / 9 / EG – Ermittlung der Prüfnotwendigkeit gemäß §14 Abs. 6 BetrSichVGMBl. Nr. 25, S. 527 v. 15.06.2009

TRBS 1201 (Oktober 2009) Teil 4 Prüfung von über-wachungsbedürftigen Anlagen – Prüfung von Aufzugs-anla-gen GMBl. Nr. 77, S. 1598 v. 20.11.2009

TRBS 1203 (März 2010) (Neufassung) Befähigte PersonenGMBl. Nr. 29, S. 627 v. 12.05.2010

PTB Hinweise, http://www.explosionsschutz.ptb.deSeveral other standards and drafts of standards



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